Nissan Sentra B18 (2020-2025) Service Manual: System

Nissan Sentra B18 (2020-2025) Service Manual / Brakes / Brake Control System :: Vdc/tcs/abs / System Description / System

Brake Control System

System Description

System Description

SYSTEM DIAGRAM

The system switches fluid pressure of each brake caliper to increase, to hold, or to decrease according to signals from control unit in ABS actuator and electric unit (control unit). This control system is applied to VDC, TCS, ABS, EBD, hill start assist function and brake assist functions.
Fail-safe function is available for each function and is activated by each function when system malfunction occurs.

INPUT SIGNAL AND OUTPUT SIGNAL

Major signal transmission between each unit via communication lines is shown in the following table:

Component	Signal description
Chassis control module (with built in steering angle sensor)	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Steering angle sensor signal Steering angle sensor malfunction signal Intelligent trace control signal Active ride control signal
ECM (Engine Control Module)	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Accelerator pedal position signal Engine speed signal Engine torque signal Target throttle position signal Mainly receives the following signal from ABS actuator and electric unit (control unit) via CAN communication: Engine torque request signal
TCM (Transmission Control Module)	Mainly transmits the following signal to ABS actuator and electric unit (control unit) via CAN communication: Current gear position signal
BCM	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Brake pedal position switch signal Stop lamp switch signal Ignition switch ON signal
Combination meter	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Brake fluid level switch signal Parking brake switch signal Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication: ABS warning lamp signal Brake warning lamp signal VDC OFF indicator lamp signal Slip indicator lamp signal

VALVE OPERATION (VDC AND TCS FUNCTIONS)

The control unit built into the ABS actuator and electric unit (control unit) controls fluid pressure of the brake calipers by operating each valve.

VDC and TCS Functions are Operating (Pressure Increases)

Name	Not activated	Pressure increases
Cut valve 1	Power supply is not supplied (open)	Power supply is supplied (close)
Cut valve 2	Power supply is not supplied (open)	Power supply is supplied (close)
Suction valve 1	Power supply is not supplied (close)	Power supply is supplied (open)
Suction valve 2	Power supply is not supplied (close)	Power supply is supplied (open)
ABS IN valve	Power supply is not supplied (open)	Power supply is not supplied (open)
ABS OUT valve	Power supply is not supplied (close)	Power supply is not supplied (close)
Each brake caliper (fluid pressure)	—	Pressure increases

Front RH brake caliper

Brake fluid is conveyed to the pump from the master cylinder through suction valve 1 and is pressurized by the pump operation. The pressurized brake fluid is supplied to the front RH brake caliper through the ABS IN valve. For the left caliper, brake fluid pressure is maintained because the pressurization is unnecessary. The pressurization for the left caliper is controlled separately from the right caliper.

Front LH brake caliper

Brake fluid is conveyed to the pump from the master cylinder through suction valve 2 and is pressurized by the pump operation. The pressurized brake fluid is supplied to the front LH brake caliper through the ABS IN valve. For the right caliper, brake fluid pressure is maintained because the pressurization is unnecessary. The pressurization for the right caliper is controlled separately from the left caliper.

Rear RH brake caliper

Brake fluid is conveyed to the pump from the master cylinder through suction valve 2 and is pressurized by the pump operation. The pressurized brake fluid is supplied to the rear RH brake caliper through the ABS IN valve. For the left caliper, brake fluid pressure is maintained because the pressurization is unnecessary. The pressurization for the left caliper is controlled separately from the right caliper.

Rear LH brake caliper

Brake fluid is conveyed to the pump from the master cylinder through suction valve 1 and is pressurized by the pump operation. The pressurized brake fluid is supplied to the rear LH brake caliper through the ABS IN valve. For the right caliper, brake fluid pressure is maintained because the pressurization is unnecessary. The pressurization for the right caliper is controlled separately from the left caliper.

VDC and TCS Functions Start Operating (Pressure Holds)

Name	Not activated	Pressure holds
Cut valve 1	Power supply is not supplied (open)	Power supply is supplied (close)
Cut valve 2	Power supply is not supplied (open)	Power supply is supplied (close)
Suction valve 1	Power supply is not supplied (close)	Power supply is not supplied (close)
Suction valve 2	Power supply is not supplied (close)	Power supply is not supplied (close)
ABS IN valve	Power supply is not supplied (open)	Power supply is not supplied (open)
ABS OUT valve	Power supply is not supplied (close)	Power supply is not supplied (close)
Each brake caliper (fluid pressure)	—	Pressure holds

Front RH brake caliper

Since the cut valve 1 and the suction valve 1 are closed, the front RH brake caliper, master cylinder, and reservoir are blocked. This maintains fluid pressure applied on the front RH brake caliper. The pressurization for the left caliper is controlled separately from the right caliper.

Front LH brake caliper

Since the cut valve 2 and the suction valve 2 are closed, the front LH brake caliper, master cylinder, and reservoir are blocked. This maintains fluid pressure applied on the front LH brake caliper. The pressurization for the right caliper is controlled separately from the left caliper.

Rear RH brake caliper

Since the cut valve 2 and the suction valve 2 are closed, the rear RH brake caliper, master cylinder, and reservoir are blocked. This maintains fluid pressure applied on the rear RH brake caliper. The pressurization for the left caliper is controlled separately from the right caliper.

Rear LH brake caliper

Since the cut valve 1 and the suction valve 1 are closed, the rear LH brake caliper, master cylinder, and reservoir are blocked. This maintains fluid pressure applied on the rear LH brake caliper. The pressurization for the right caliper is controlled separately from the left caliper.

VDC and TCS Functions Operating (Pressure Decreases)

Name	Not activated	Pressure decreases
Cut valve 1	Power supply is not supplied (open)	Power supply is not supplied (open)
Cut valve 2	Power supply is not supplied (open)	Power supply is not supplied (open)
Suction valve 1	Power supply is not supplied (close)	Power supply is not supplied (close)
Suction valve 2	Power supply is not supplied (close)	Power supply is not supplied (close)
ABS IN valve	Power supply is not supplied (open)	Power supply is not supplied (open)
ABS OUT valve	Power supply is not supplied (close)	Power supply is not supplied (close)
Each brake caliper (fluid pressure)	—	Pressure decreases

Front RH brake caliper

Since the suction valve 1 and the ABS OUT valve are closed and the cut valve 1 and the ABS IN valve are open, the fluid pressure applied on the front RH brake caliper is reduced by supplying the fluid pressure to the master cylinder via the ABS IN valve and the cut valve 1. The pressurization for the right caliper is controlled separately from the left caliper.

Front LH brake caliper

Since the suction valve 2 and the ABS OUT valve are closed and the cut valve 2 and the ABS IN valve are open, the fluid pressure applied on the front LH brake caliper is reduced by supplying the fluid pressure to the master cylinder via the ABS IN valve and the cut valve 2. The pressurization for the left caliper is controlled separately from the right caliper.

Rear RH brake caliper

Since the suction valve 2 and the ABS OUT valve are closed and the cut valve 2 and the ABS IN valve are open, the fluid pressure applied on the rear RH brake caliper is reduced by supplying the fluid pressure to the master cylinder via the ABS IN valve and the cut valve 2. The pressurization for the right caliper is controlled separately from the left caliper.

Rear LH brake caliper

Since the suction valve 1 and the ABS OUT valve are closed and the cut valve 1 and the ABS IN valve are open, the fluid pressure applied on the rear LH brake caliper is reduced by supplying the fluid pressure to the master cylinder via the ABS IN valve and the cut valve 1. The pressurization for the right caliper is controlled separately from the left caliper.

Component Parts and Function

Component	Function
Pump	Returns the brake fluid reserved in reservoir to master cylinder by reducing pressure.
Motor	Activates the pump according to signals from ABS actuator and electric unit (control unit).
Cut valve 1 Cut valve 2	Shuts off the ordinary brake line from master cylinder.
Suction valve 1 Suction valve 2	Supplies the brake fluid from master cylinder to the pump.
ABS IN valve	Switches the fluid pressure line to increase or hold according to signals from control unit.
ABS OUT valve	Switches the fluid pressure line to increase, hold or decrease according to signals from control unit.
Return check valve	Returns the brake fluid from brake caliper to master cylinder by bypassing orifice of each valve when brake is released.
Reservoir	Temporarily reserves the brake fluid drained from brake caliper so that pressure efficiently decreases when decreasing pressure of brake caliper.
Pressure sensor	Detects the brake fluid pressure and transmits signal to ABS actuator and electric unit (control unit).

VALVE OPERATION (ABS AND EBD FUNCTIONS)

The control unit built into the ABS actuator and electric unit (control unit) controls fluid pressure of the brake calipers by operating each valve.

Brake Pedal Applied or ABS Function Operating (Pressure Increases)

Name	Not activated	Pressure increases
Cut valve 1	Power supply is not supplied (open)	Power supply is not supplied (open)
Cut valve 2	Power supply is not supplied (open)	Power supply is not supplied (open)
Suction valve 1	Power supply is not supplied (close)	Power supply is not supplied (close)
Suction valve 2	Power supply is not supplied (close)	Power supply is not supplied (close)
ABS IN valve	Power supply is not supplied (open)	Power supply is not supplied (open)
ABS OUT valve	Power supply is not supplied (close)	Power supply is not supplied (close)
Each brake caliper (fluid pressure)	—	Pressure increases

Front RH brake caliper

When the cut valve 1 and the ABS IN valve opens, brake fluid is supplied to the front RH brake caliper from the master cylinder through the ABS IN valve. Brake fluid does not flow into the reservoir because the ABS OUT valve is closed.

Front LH brake caliper

When the cut valve 2 and the ABS IN valve opens, brake fluid is supplied to the front LH brake caliper from the master cylinder through the ABS IN valve. Brake fluid does not flow into the reservoir because the ABS OUT valve is closed.

Rear RH brake caliper

When the cut valve 2 and the ABS IN valve opens, brake fluid is supplied to the rear RH brake caliper from the master cylinder through the ABS IN valve. Brake fluid does not flow into the reservoir because the ABS OUT valve is closed.

Rear LH brake caliper

When the cut valve 1 and the ABS IN valve opens, brake fluid is supplied to the rear LH brake caliper from the master cylinder through the ABS IN valve. Brake fluid does not flow into the reservoir because the ABS OUT valve is closed.

ABS Function Starts Operating (Pressure Holds)

Name	Not activated	Pressure holds
Cut valve 1	Power supply is not supplied (open)	Power supply is not supplied (open)
Cut valve 2	Power supply is not supplied (open)	Power supply is not supplied (open)
Suction valve 1	Power supply is not supplied (close)	Power supply is not supplied (close)
Suction valve 2	Power supply is not supplied (close)	Power supply is not supplied (close)
ABS IN valve	Power supply is not supplied (open)	Power supply is supplied (close)
ABS OUT valve	Power supply is not supplied (close)	Power supply is not supplied (close)
Each brake caliper (fluid pressure)	—	Pressure holds

Front RH brake caliper

Since the ABS IN valve and the ABS OUT valve are closed, the front RH brake caliper, master cylinder, and reservoir are blocked. This maintains fluid pressure applied on the front RH brake caliper.

Front LH brake caliper

Since the ABS IN valve and the ABS OUT valve are closed, the front LH brake caliper, master cylinder, and reservoir are blocked. This maintains fluid pressure applied on the front LH brake caliper.

Rear RH brake caliper

Since the ABS IN valve and the ABS OUT valve are closed, the rear RH brake caliper, master cylinder, and reservoir are blocked. This maintains fluid pressure applied on the rear RH brake caliper.

Rear LH brake caliper

Since the ABS IN valve and the ABS OUT valve are closed, the rear LH brake caliper, master cylinder, and reservoir are blocked. This maintains fluid pressure applied on the rear LH brake caliper.

ABS Function Operating (Pressure Decreases)

Name	Not activated	Pressure decreases
Cut valve 1	Power supply is not supplied (open)	Power supply is not supplied (open)
Cut valve 2	Power supply is not supplied (open)	Power supply is not supplied (open)
Suction valve 1	Power supply is not supplied (close)	Power supply is not supplied (close)
Suction valve 2	Power supply is not supplied (close)	Power supply is not supplied (close)
ABS IN valve	Power supply is not supplied (open)	Power supply is supplied (close)
ABS OUT valve	Power supply is not supplied (close)	Power supply is supplied (open)
Each brake caliper (fluid pressure)	—	Pressure decreases

Front RH brake caliper

Since the ABS IN valve is closed and the ABS OUT valve is opened, fluid pressure applied on the front RH brake caliper is supplied to the reservoir through the ABS OUT valve. This fluid pressure decreases when sent to the master cylinder by the pump.

Front LH brake caliper

Since the ABS IN valve is closed and the ABS OUT valve is opened, fluid pressure applied on the front LH brake caliper is supplied to the reservoir through the ABS OUT valve. This fluid pressure decreases when sent to the master cylinder by the pump.

Rear RH brake caliper

Since the ABS IN valve is closed and the ABS OUT valve is opened, fluid pressure applied on the rear RH brake caliper is supplied to the reservoir through the ABS OUT valve. This fluid pressure decreases when sent to the master cylinder by the pump.

Rear LH brake caliper

Since the ABS IN valve is closed and the ABS OUT valve is opened, fluid pressure applied on the rear LH brake caliper is supplied to the reservoir through the ABS OUT valve. This fluid pressure decreases when sent to the master cylinder by the pump.

ABS Function Operating (Pressure Increases)

Name	Not activated	Pressure increases
Cut valve 1	Power supply is not supplied (open)	Power supply is not supplied (open)
Cut valve 2	Power supply is not supplied (open)	Power supply is not supplied (open)
Suction valve 1	Power supply is not supplied (close)	Power supply is not supplied (close)
Suction valve 2	Power supply is not supplied (close)	Power supply is not supplied (close)
ABS IN valve	Power supply is not supplied (open)	Power supply is not supplied (open)
ABS OUT valve	Power supply is not supplied (close)	Power supply is not supplied (close)
Each brake caliper (fluid pressure)	—	Pressure increases

Front RH brake caliper

Brake fluid is supplied to the front RH brake caliper from the master cylinder through the cut valve 1 and the ABS IN valve. Since the suction valve 1 and the ABS OUT valve are closed, the fluid does not flow into the reservoir. The amount of brake fluid supplied to the front RH brake caliper from the master cylinder is controlled according to time that the ABS IN valve is not energized (time that the ABS IN valve is open).

Front LH brake caliper

Brake fluid is supplied to the front LH brake caliper from the master cylinder through the cut valve 2 and the ABS IN valve. Since the suction valve 2 and the ABS OUT valve are closed, the fluid does not flow into the reservoir. The amount of brake fluid supplied to the front LH brake caliper from the master cylinder is controlled according to time that the ABS IN valve is not energized (time that the ABS IN valve is open).

Rear RH brake caliper

Brake fluid is supplied to the rear RH brake caliper from the master cylinder through the cut valve 2 and the ABS IN valve. Since the suction valve 2 and the ABS OUT valve are closed, the fluid does not flow into the reservoir. The amount of brake fluid supplied to the rear RH brake caliper from the master cylinder is controlled according to time that the ABS IN valve is not energized (time that the ABS IN valve is open).

Rear LH brake caliper

Brake fluid is supplied to the rear LH brake caliper from the master cylinder through the cut valve 1 and the ABS IN valve. Since the suction valve 1 and the ABS OUT valve are closed, the fluid does not flow into the reservoir. The amount of brake fluid supplied to the rear LH brake caliper from the master cylinder is controlled according to time that the ABS IN valve is not energized (time that the ABS IN valve is open).

Brake Release

Name	Not activated	During brake release
Cut valve 1	Power supply is not supplied (open)	Power supply is not supplied (open)
Cut valve 2	Power supply is not supplied (open)	Power supply is not supplied (open)
Suction valve 1	Power supply is not supplied (close)	Power supply is not supplied (close)
Suction valve 2	Power supply is not supplied (close)	Power supply is not supplied (close)
ABS IN valve	Power supply is not supplied (open)	Power supply is not supplied (open)
ABS OUT valve	Power supply is not supplied (close)	Power supply is not supplied (close)
Each brake caliper (fluid pressure)	—	Pressure decreases

Front RH brake caliper

Brake fluid is supplied to the front RH brake caliper through the return check valve of the ABS IN valve and the cut valve 1 and returns to the master cylinder.

Front LH brake caliper

Brake fluid is supplied to the front LH brake caliper through the return check valve of the ABS IN valve and the cut valve 2 and returns to the master cylinder.

Rear RH brake caliper

Brake fluid is supplied to the rear RH brake caliper through the return check valve of the ABS IN valve and the cut valve 2 and returns to the master cylinder.

Rear LH brake caliper

Brake fluid is supplied to the rear LH brake caliper through the return check valve of the ABS IN valve and the cut valve 1 and returns to the master cylinder.

Component Parts and Function

Component	Function
Pump	Returns the brake fluid reserved in reservoir to master cylinder by reducing pressure.
Motor	Activates the pump according to signals from ABS actuator and electric unit (control unit).
Cut valve 1 Cut valve 2	Shuts off the ordinary brake line from master cylinder.
Suction valve 1 Suction valve 2	Supplies the brake fluid from master cylinder to the pump.
ABS IN valve	Switches the fluid pressure line to increase or hold according to signals from control unit.
ABS OUT valve	Switches the fluid pressure line to increase, hold or decrease according to signals from control unit.
Return check valve	Returns the brake fluid from brake caliper to master cylinder by bypassing orifice of each valve when brake is released.
Reservoir	Temporarily reserves the brake fluid drained from brake caliper, so that pressure efficiently decreases when decreasing pressure of brake caliper.
Pressure sensor	Detects the brake fluid pressure and transmits signal to ABS actuator and electric unit (control unit).

CONDITIONS FOR INDICATOR LAMP ILLUMINATION

Turns ON when VDC and TCS functions are switched to non-operational status (OFF) by VDC OFF selection in the information display of the combination meter.
Turns ON when ignition switch is placed in the ON position and turns OFF when the system is normal for bulb check purposes.

Condition (status)	VDC OFF indicator lamp	Slip indicator lamp
Ignition switch OFF	OFF	OFF
For approx. 1 second after the ignition switch is placed ON	ON	ON
Approx. 2 seconds after ignition switch is placed ON (when the system is in normal operation)	OFF	OFF
When VDC OFF selection is ON (VDC function and TCS function are OFF.)	ON	OFF
VDC function is malfunctioning.	OFF	ON
TCS function is malfunctioning.	OFF	ON

CONDITIONS FOR WARNING LAMP ILLUMINATION

Turns ON when ignition switch is ON and turns OFF when the system is normal for bulb check purposes.

Condition (status)	ABS warning lamp	Brake warning lamp
Ignition switch OFF	OFF	OFF
For approx. 1 second after the ignition switch is placed ON	ON	ON
Approx. 2 seconds after ignition switch is placed ON (when the system is in normal operation)	OFF	OFF
After engine starts	OFF	OFF
When parking brake operates (parking brake switch ON)	OFF	ON
When brake fluid is less than the specified level (brake fluid level switch ON)	OFF	ON
VDC function is malfunctioning.	OFF	OFF
TCS function is malfunctioning.	OFF	OFF
ABS function is malfunctioning.	ON	OFF
EBD function is malfunctioning.	ON	ON
VDC function is operating.	OFF	OFF
TCS function is operating.	OFF	OFF
Brake assist	OFF	OFF
Brake assist function is malfunctioning	OFF	OFF
Hill start assist function is malfunctioning	OFF	OFF

Vdc Function

System Description

System Description

SYSTEM DIAGRAM

Side slip or tail slip may occur while driving on a slippery road or intending urgent evasive driving. VDC function detects side slip status using each sensor when side slip or tail slip is about to occur and improves Nissan Sentra vehicle stability by brake control and engine output control during driving.
In addition to ABS function, EBD function and TCS function, target side slip amount is calculated according to steering operation amount from steering angle sensor and brake operation amount from brake pressure sensor. By comparing this information with Nissan Sentra vehicle side slip amount that is calculated from information from yaw rate/side/decel G sensor and wheel sensor, Nissan Sentra vehicle driving conditions (conditions of understeer or oversteer) are judged and vehicle stability is improved by brake force control on all wheels and engine output control.
VDC function can be switched to non-operational status (OFF) by operating VDC OFF switch. In this case, VDC OFF indicator lamp turns ON.
Control unit portion automatically improves driving stability by performing brake force control as well as engine output control by transmitting drive signal to actuator portion according to difference between target side slip amount and Nissan Sentra vehicle side slip amount.
VDC warning lamp blinks while VDC function is in operation and indicates to the driver that the function is in operation.
CONSULT can be used to diagnose the system diagnosis.
Fail-safe function is adopted. When a malfunction occurs in VDC function, the control is suspended for VDC function, TCS function, brake assist function and brake force distribution function. The Nissan Sentra vehicle status becomes the same as models without VDC function, TCS function and brake assist function. However, ABS function and EBD function are operated normally. Refer to Fail-Safe.

INPUT SIGNAL AND OUTPUT SIGNAL

Major signal transmission between each unit via communication lines is shown in the following table:

Component	Signal description
ECM	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Accelerator pedal position signal Engine speed signal Engine torque signal Target throttle position signal Mainly receives the following signal from ABS actuator and electric unit (control unit) via CAN communication: Engine torque request signal
TCM	Mainly transmits the following signal to ABS actuator and electric unit (control unit) via CAN communication: Current gear position signal
Combination meter	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Brake fluid level switch signal Parking brake switch signal Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication: ABS warning lamp signal Brake warning lamp signal VDC OFF indicator lamp signal Slip indicator lamp signal
BCM	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Stop lamp switch signal Brake pedal position switch signal Ignition switch ON signal
Chassis control module (with built in steering angle sensor)	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Steering angle sensor signal Steering angle sensor malfunction signal Intelligent trace control signal Active ride control signal

OPERATION CHARACTERISTICS

VDC Function That Prevents Oversteer Tendency

During cornering, brake force (brake fluid pressure) is applied on front wheel and rear wheel on the outer side of turn. Momentum directing towards the outer side of turn is generated. Oversteer is prevented.
When changing driving lane on a slippery road when oversteer tendency is judged large, engine output is controlled as well as brake force (brake fluid pressure) of four wheels. Oversteer tendency decreases.

VDC Function That Prevents Understeer Tendency

During cornering, brake force (brake fluid pressure) is applied on front wheel and rear wheel on the inner side of turn. Momentum directing toward the inner side of turn is generated. Understeer is prevented.
When applying braking during cornering on a slippery road when understeer tendency is judged large, engine output is controlled as well as brake force (brake fluid pressure) of four wheels. Understeer tendency decreases.

Tcs Function

System Description

System Description

SYSTEM DIAGRAM

Wheel spin status of drive wheel is detected by wheel sensor of four wheels. Engine output and transmission shift status are controlled so that slip rate of drive wheels is in appropriate level. When wheel spin occurs on drive wheel, ABS actuator and electric unit (control unit) performs brake force control of LH and RH drive wheels (applies brake force by increasing brake fluid pressure of drive wheel) and decreases engine torque by engine torque control. Wheel spin amount decreases. Engine torque is controlled to appropriate level.
TCS function can be switched to non-operational status (OFF) by operating VDC OFF switch. In this case, VDC OFF indicator lamp turns ON.
VDC warning lamp blinks while TCS function is in operation and indicates to the driver that the function is in operation.
CONSULT can be used to diagnose the system diagnosis.
Fail-safe function is adopted. When a malfunction occurs in TCS function, the control is suspended for VDC function, TCS function and brake assist function. The Nissan Sentra vehicle status becomes the same as models without VDC function, TCS function and brake assist function. However, ABS function and EBD function are operated normally. Refer to Fail-Safe.

INPUT SIGNAL AND OUTPUT SIGNAL

Major signal transmission between each unit via communication lines is shown in the following table:

Component	Signal description
ECM	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Accelerator pedal position signal Engine speed signal Engine torque signal Target throttle position signal Mainly receives the following signal from ABS actuator and electric unit (control unit) via CAN communication: Engine torque request signal
TCM	Mainly transmits the following signal to ABS actuator and electric unit (control unit) via CAN communication: Current gear position signal
Combination meter	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Brake fluid level switch signal Parking brake switch signal Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication: ABS warning lamp signal Brake warning lamp signal VDC OFF indicator lamp signal Slip indicator lamp signal
BCM	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Stop lamp switch signal Brake pedal position switch signal Ignition switch ON signal
Chassis control module (with built in steering angle sensor)	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Steering angle sensor signal Steering angle sensor malfunction signal Intelligent trace control signal Active ride control signal

Abs Function

System Description

System Description

SYSTEM DIAGRAM

By preventing wheel lock through brake force (brake fluid pressure) control that is electronically controlled by detecting wheel speed during braking, stability during emergency braking is improved so that obstacles can be easily bypassed by steering operation.
During braking, control units calculate wheel speed and pseudo-Nissan Sentra vehicle speed and transmits pressure increase, hold or decrease signals to actuator portion according to wheel slip status.
The following effects are obtained by preventing wheel lock during braking:
- Nissan Sentra Vehicle tail slip is prevented during braking when driving straight.
- Understeer and oversteer tendencies are moderated during braking on a corner.
- Obstacles may be easily bypassed by steering operation during braking.
CONSULT can be used to diagnose the system diagnosis.
Fail-safe function is adopted. When a malfunction occurs in ABS function, the control is suspended for VDC function, TCS function and ABS function. The Nissan Sentra vehicle status becomes the same as models without VDC function, TCS function, ABS function and brake assist function. However, EBD function is operated normally. Refer to Fail-Safe.

Note:

ABS has the characteristics as described here. This is not a device that helps reckless driving.
To stop Nissan Sentra vehicle efficiently, ABS does not operate and ordinary brake operates at low speed [approx. 6 MPH (10 km/h) or less, but differs subject to road conditions].
Self-diagnosis is performed immediately after engine starts and when Nissan Sentra vehicle is initially driven [vehicle speed approx. 9 MPH (15 km/h)]. Motor sounds are generated during self-diagnosis. In addition, brake pedal may be feel heavy when depressing brake pedal lightly. These symptoms are not malfunctions.

INPUT SIGNAL AND OUTPUT SIGNAL

Major signal transmission between each unit via communication lines is shown in the following table:

Component	Signal description
Combination meter	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Brake fluid level switch signal Parking brake switch signal Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication: ABS warning lamp signal Brake warning lamp signal VDC OFF indicator lamp signal Slip indicator lamp signal
BCM	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Stop lamp switch signal Brake pedal position switch signal Ignition switch ON signal
Chassis control module (with built in steering angle sensor)	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Steering angle sensor signal Steering angle sensor malfunction signal Intelligent trace control signal Active ride control signal

Component

Signal description

Combination meter

Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication:

Brake fluid level switch signal
Parking brake switch signal

Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication:

ABS warning lamp signal
Brake warning lamp signal
VDC OFF indicator lamp signal
Slip indicator lamp signal

BCM

Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication:

Stop lamp switch signal
Brake pedal position switch signal
Ignition switch ON signal

Chassis control module (with built in steering angle sensor)

Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication:

Steering angle sensor signal
Steering angle sensor malfunction signal
Intelligent trace control signal
Active ride control signal

Ebd Function

System Description

System Description

SYSTEM DIAGRAM

By preventing rear wheel slip increase through rear wheel brake force (brake fluid pressure) control that is electronically controlled when slight slip of front and rear wheels is detected during braking, stability during braking is improved.
EBD function is expanded and developed from conventional ABS function and corrects rear wheel brake force to appropriate level by electronic control according to load weight (number of passengers).
During braking, control unit portion compares slight slip of front and rear wheels with wheel speed sensor signal, transmits drive signal to actuator portion when rear wheel slip exceeds front wheel slip for the specified value or more, and controls rear wheel brake force (brake fluid pressure) so that increase of rear wheel slip is prevented and slips of front wheel and rear wheel are nearly equalized. ABS control is applied when slip of each wheel increases and wheel speed is the threshold value of ABS control or less.
CONSULT can be used to diagnose the system diagnosis.
Fail-safe function is adopted. When a malfunction occurs in EBD function, the control is suspended for VDC function, TCS function, ABS function, EBD function and brake assist function. The Nissan Sentra vehicle status becomes the same as models without VDC function, TCS function, ABS function, EBD function and brake assist function. Refer to Fail-Safe.

INPUT SIGNAL AND OUTPUT SIGNAL

Major signal transmission between each unit via communication lines is shown in the following table:

Component	Signal description
BCM	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Stop lamp switch signal Brake pedal position switch signal Ignition switch ON signal
Combination meter	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Brake fluid level switch signal Parking brake switch signal Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication: ABS warning lamp signal Brake warning lamp signal VDC OFF indicator lamp signal Slip indicator lamp signal

Component

Signal description

BCM

Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication:

Stop lamp switch signal
Brake pedal position switch signal
Ignition switch ON signal

Combination meter

Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication:

Brake fluid level switch signal
Parking brake switch signal

Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication:

ABS warning lamp signal
Brake warning lamp signal
VDC OFF indicator lamp signal
Slip indicator lamp signal

Hill Start Assist Function

System Description

System Description

This function maintains brake fluid pressure so that the vehicle does not move backwards even if brake pedal is released to depress accelerator pedal to start the Nissan Sentra vehicle while it is stopped on an uphill slope by depressing brake pedal.
This function operates when the Nissan Sentra vehicle is in stop status on a uphill slope of slope ratio 10% or more and selector lever is in the position other than P or N.
Hill start assist function is only for the start aid. It maintains the brake fluid pressure for approx. 2 seconds after releasing the brake pedal, and then decreases the pressure gradually. If the Nissan Sentra vehicle can start by the accelerator operation, the brake is released automatically and a smooth start can be performed.
Fail-safe function is adopted. When a malfunction occurs in hill start assist function, the control is suspended for VDC function, TCS function, Brake assist function, hill start assist function and Brake force distribution function. The Nissan Sentra vehicle status becomes the same as models without VDC function, TCS function, Brake assist function, hill start assist function and Brake force distribution function. However, ABS function and EBD function are operated normally. Refer to Fail-Safe.

SYSTEM DIAGRAM

INPUT SIGNAL AND OUTPUT SIGNAL

Major signal transmission between each unit via communication lines is shown in the following table:

Component	Signal description
BCM	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Stop lamp switch signal Brake pedal position switch signal Ignition switch ON signal
Combination meter	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Brake fluid level switch signal Parking brake switch signal Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication: ABS warning lamp signal Brake warning lamp signal VDC OFF indicator lamp signal Slip indicator lamp signal

Component

Signal description

BCM

Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication:

Stop lamp switch signal
Brake pedal position switch signal
Ignition switch ON signal

Combination meter

Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication:

Brake fluid level switch signal
Parking brake switch signal

Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication:

ABS warning lamp signal
Brake warning lamp signal
VDC OFF indicator lamp signal
Slip indicator lamp signal

Intelligent Trace Control Function

System Description

System Description

Intelligent trace control function controls the braking utilizing the ABS actuator and electric unit (control unit), depending on cornering condition calculated from driver's steering input and plural sensors.
Intelligent trace control function is aimed to enhance traceability at corners and smooth the Nissan Sentra vehicle movement to provide confident driving.
When the VDC is turned OFF the VDC system, the intelligent trace control system is also turned OFF.
When the intelligent trace control is operated, intelligent trace control graphics are shown on the information display of combination meter. These are shown only when “Chassis control” is selected on the information display. Refer to System Description.
When the intelligent trace control is not functioning properly, the master warning lamp illuminates. Warning message “Chassis control” will also appear on information display.

Note:

The intelligent trace control may not be effective depending on the driving condition. Always driving carefully and attentively.
Brake pedal may vibrate and brake pedal feel may change during intelligent trace control operation. Also operation noise may be noticeable during operation. These are not abnormal conditions.
When the intelligent trace control is selected OFF, some functions will be kept ON to assist driver. (For example, avoidance condition.)

OPERATION CHARACTERISTICS

Intelligent trace control helps enhance the transition from braking into and then accelerating out of corners. Intelligent trace control utilizes the Nissan Sentra vehicle′s electrically-driven intelligent brake system to help improve cornering feel by automatically applying brakes. Furthermore, Intelligent trace control will apply selective braking to help create increased steering response in S-turns. For example, if driving through an S-turn that starts with steering to the right, the right-side brakes are engaged to create a yaw momentum and help turn the Nissan Sentra vehicle.

Brake control amount is controlled according to steering operation status by the driver and Nissan Sentra vehicle cornering status.
During cornering, the brake control system limits changes in steering angle by controlling the inner ring brakes according to accelerator pedal operation and allows smooth movement of the Nissan Sentra vehicle to achieve stable cornering.

SYSTEM DIAGRAM

INPUT SIGNAL AND OUTPUT SIGNAL

Major signal transmission between each unit via communication lines is shown in the following table:

Component	Signal description
ECM	Mainly transmits the following signals to chassis control module via CAN communication: Accelerator pedal position signal Engine torque signal Engine speed signal
TCM	Mainly transmits the following signal to chassis control module via CAN communication: Current gear position signal
ABS actuator and electric unit (control unit)	Mainly transmits the following signals to chassis control module via CAN communication: Front LH wheel speed signal Front RH wheel speed signal Rear LH wheel speed signal Rear RH wheel speed signal ABS operation signal TCS operation signal VDC operation signal Stop lamp switch signal Nissan Sentra Vehicle speed signal (ABS) Yaw rate signal Side G signal Decel G signal VDC OFF switch signal Brake fluid pressure signal Steering angle sensor signal Mainly receives the following signal from chassis control module via CAN communication: Intelligent trace control signal
Chassis control module (with built-in steering angle sensor)	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Steering angle sensor signal Steering angle sensor malfunction signal Intelligent trace control signal Active ride control signal
Combination meter	Mainly receives the following signals from chassis control module via CAN communication: Chassis control malfunction signal Intelligent trace control display signal

Brake Assist Function

System Description

System Description

SYSTEM DIAGRAM

When the driver brakes hard in an emergency, the stopping distance is reduced by increasing brake fluid pressure.
Fail-safe function is adopted. When a malfunction occurs in brake assist function, the control is suspended for VDC function, TCS function and brake assist function. The Nissan Sentra vehicle status becomes the same as models without VDC function, TCS function and brake assist function. However, ABS function and EBD function are operated normally. Refer to Fail-Safe.

INPUT SIGNAL AND OUTPUT SIGNAL

Major signal transmission between each unit via communication lines is shown in the following table:

Component	Signal description
ECM	Mainly transmits the following signal to ABS actuator and electric unit (control unit) via CAN communication: Accelerator pedal position signal Engine speed signal Engine torque signal Mainly receives the following signal from ABS actuator and electric unit (control unit) via CAN communication: Engine torque request signal
TCM	Mainly transmits the following signal to ABS actuator and electric unit (control unit) via CAN communication: Current gear position signal
Combination meter	Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication: Brake fluid level switch signal Parking brake switch signal Mainly receives the following signals from ABS actuator and electric unit (control unit) via CAN communication: VDC warning lamp signal VDC OFF indicator lamp signal
BCM	Transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Stop lamp switch signal Brake pedal position switch signal Ignition switch ON signal
Chassis control module (with built-in steering angle sensor)	Mainly transmits the following signals to ABS actuator and electric unit (control unit) via CAN communication: Steering angle sensor signal Steering angle sensor malfunction signal

Warning/indicator/chime List

Warning Lamp/indicator Lamp

Warning Lamp/Indicator Lamp

Name	Design	Layout/Function
ABS warning lamp	or	For function: Refer to Component Function Check.
ABS warning lamp	or	For layout: Refer to Design (Type A) or Design (Type B).
Brake warning lamp	or	For function: Refer to Component Function Check.
Brake warning lamp	or	For layout: Refer to Design (Type A) or Design (Type B).
VDC OFF indicator lamp		For function: Refer to Component Function Check.
VDC OFF indicator lamp		For layout: Refer to Design (Type A) or Design (Type B).
VDC warning lamp		For function: Refer to Component Function Check.
VDC warning lamp		For layout: Refer to Design (Type A) or Design (Type B).

Component Parts

Brake Control System Component Parts Location Component Parts Location A. ...

Diagnosis System [abs Actuator and Electric Unit (control Unit)]

Consult Function CONSULT Function APPLICATION ITEMS CONSULT can display each diagnostic item using the diagnostic test modes as follows: ...

Other materials:

Dtc/circuit diagnosis
Malfunction area chart Main line Branch line Short circuit Main line between ipdm-e and dlc circuit Diagnosis procedure 1.Check connector Turn the ignition switch off. Disconnect the battery cable from the negative terminal. Check the following terminals and connectors fo ...

Precaution
Precaution for Supplemental Restraint System (SRS) "AIR BAG" and "SEAT BELT PRE-TENSIONER" The Supplemental Restraint System such as вЂњAIR BAGвЂќ and вЂњSEAT BELT PRE-TENSIONERвЂќ, used along with a front seat belt, helps to reduce the risk or severity of injur ...

Tow Truck Towing
Tow Truck Towing Tow Truck Towing Warning: Never ride in a vehicle that is being towed. Never get under your Nissan Sentra vehicle after it has been lifted by a tow truck. CAUTION: All app ...