Nissan Sentra B18 (2020-2025) Service Manual: Diagnosis System (av Control Unit)

Nissan Sentra B18 (2020-2025) Service Manual / Driver Information & Multimedia / Audio, Visual & Navigation System :: Display Audio Without Bose with 8" Color Display / System Description / Diagnosis System (av Control Unit)

Description

Description

The AV control unit on board diagnosis performs the following functions listed in the table below:

Mode		Description
Self Diagnosis		Audio system diagnosis. Diagnoses the connections across system components.
Confirmation/Adjustment	Display Diagnosis	The following check functions are available: Color Spectrum Bar Gradation Bar Touch Panel White Display Screenshot to USB y-curve
	Nissan Sentra Vehicle Signals	Diagnosis of signals can be performed for Nissan Sentra Vehicle Speed, Ignition, Illumination Control, MR out, Illumination Switch, Reverse, Parking Brake and ACC.
	Navigation	Displayed, but not used.
	Error Location Display	The system malfunction and the frequency when occurring in the past are displayed. When the malfunctioning item is selected, the time that the selected malfunction last occurred is displayed.
	AV COMM Diagnosis	The AV communication condition of each unit of audio system can be monitored.
	### Hands-Free Phone	Maintenance can be performed.
	Camera	The following functions are available: Correct Draw Line of Rear View Camera Alter/Confirm Configuration Route Simulation
	Delete Unit Connection Log	Erase the connection history of unit.
	Initialize Settings	User Data Initialization is available.
	GPS Time Set	Displayed, but not used.
	Version Information	Version information of the Multi AV system is displayed.
	Software Update	Software of the AV control unit can be updated. Update history can be viewed.
	### Speaker Test	Individual speakers can be checked at the 100Hz and 4KHz range.
	Radio Tuner	FM Monitor and AM Monitor information can be observed.
	SXM	SXM Monitor information can be observed.

Perform CONSULT diagnosis if the AV control unit on board diagnosis does not start, or the screen does not display anything.

On Board Diagnosis Function

On Board Diagnosis Function

METHOD OF STARTING

AV Control Unit Self Diagnosis

Ignition switch ON.
Audio system OFF.
While pressing the MENU button, turn the TUNE-SCROLL dial clockwise or counterclockwise for 40 clicks or more. Shifting from current screen to previous screen is performed by pressing BACK button.
The trouble diagnosis initial screen is displayed, and “Self Diagnosis” and “Confirmation/Adjustment” can be selected.

SELF-DIAGNOSIS MODE

Start the self-diagnosis function and select “Self Diagnosis”.
- Self-diagnosis subdivision screen is displayed, and the self-diagnosis mode starts.
- The bar graph visible on the center of the self-diagnosis subdivision screen indicates progress of the trouble diagnosis.

Diagnosis results are displayed after the self-diagnosis is completed. The unit names and the connection lines are color-coded according to the diagnostic results.

Diagnosis results	Unit	Connection line
Normal	Green	Green
Connection malfunction	Gray	Yellow
Unit malfunction ^Note	Red	Green

Note:

Control Unit (AV control unit) is displayed in red.

Replace AV control unit if “Self-Diagnosis did not run because of a control unit malfunction” is indicated. The symptom is AV control unit internal error. Refer to Removal and Installation.
If multiple errors occur at the same time for a single unit, the screen switch colors are determined according to the following order of priority: red > gray.

MCAN, Head Unit and VCAN are displayed:
- Press the MCAN button and the system components connected via AV communication are displayed.
- Press the Head Unit button and the components connected to the AV control unit are displayed.
- Press the VCAN button and the system components connected via CAN communication are displayed. Refer to Trouble Diagnosis Flow Chart for CAN communication diagnosis.

Detection Range of Self-diagnosis Mode

The self-diagnosis mode allows the technician to diagnose the connection in the communication line between AV control unit and each unit and the internal operation of the AV control unit.
Because the start condition of diagnosis function is a switch operation, the on board diagnosis function cannot be started up if any malfunction is detected in the AV control unit switches.

SELF-DIAGNOSIS RESULTS

Only Unit Part Is Displayed In Red (MCAN)

Screen switch

Description

Possible malfunction location / Action to take

Head Unit

Malfunction is detected in AV control unit power supply and ground circuits.

Check AV control unit power supply and ground circuits.

Refer to Diagnosis Procedure.

When no malfunction is detected in those circuits, replace AV control unit.

Refer to Removal and Installation.

TCU

Malfunction is detected in TCU power supply and ground circuits.

Check TCU power supply and ground circuits.

Refer to Diagnosis Procedure.

When no malfunction is detected in those circuits, replace TCU.

Refer to Removal and Installation.

Meter

Malfunction is detected in combination meter power supply and ground circuits.

Check combination meter power supply and ground circuits.

Refer to Diagnosis Procedure.

When no malfunction is detected in those circuits, replace combination meter.

Refer to Removal and Installation.

Only Unit Part Is Displayed In Red (Head Unit)

Screen switch	Description	Possible malfunction location / Action to take
Head Unit	Malfunction is detected in AV control unit power supply and ground circuits.	Check AV control unit power supply and ground circuits. Refer to Diagnosis Procedure. When no malfunction is detected in those circuits, replace AV control unit. Refer to Removal and Installation.
Amplifier	Malfunction is detected in the internal amplifier of the AV control unit.	Replace the AV control unit. Refer to Removal and Installation.
Conn Modules	Malfunction is detected in the internal Bluetooth^® module of the AV control unit. Malfunction is detected in the internal WiFi module of the AV control unit.	Replace the AV control unit. Refer to Removal and Installation.
Antenna	Malfunction is detected in window antenna. Malfunction is detected in satellite antenna.	Check window or satellite antenna. Refer to Antenna and Antenna Feeder (window antenna) or Diagnosis Procedure (satellite antenna). When no malfunction is detected, replace window or antenna. Refer to Removal and Installation (window antenna) or Removal and Installation (satellite antenna).
Speaker	Malfunction is detected in speaker signal circuit.	Check speaker signal circuit. Refer to: Diagnosis Procedure, Diagnosis Procedure, DTC Diagnosis Procedure or DTC Diagnosis Procedure (front tweeter). Diagnosis Procedure or Diagnosis Procedure (front door speaker). Diagnosis Procedure or Diagnosis Procedure (rear speaker). When no malfunction is detected in the circuit, replace speaker. Refer to: Removal and Installation (front tweeter). Removal and Installation (front door speaker). Removal and Installation (rear speaker).
Microphone	Malfunction is detected in microphone signal circuit.	Check microphone signal circuit. Refer to Diagnosis Procedure. When no malfunction is detected in the circuit, replace microphone. Refer to Removal and Installation.
USB	Malfunction is detected in the USB harness for the front auxiliary input jacks. Malfunction is detected in the AUX signal circuits for the front auxiliary input jacks.	Check front auxiliary input jack signal circuits. Refer to Diagnosis Procedure. When no malfunction is detected in the circuits, replace front auxiliary input jack. Refer to Removal and Installation.
FAN	Malfunction is detected in the internal fan of the AV control unit.	Replace the AV control unit. Refer to Removal and Installation.

A Connecting Cable Between Units Is Displayed In Yellow (MCAN)

Area with yellow connection lines	Description	Possible malfunction location / Action to take
Head unit ⇔ TCU	TCU AV communication connection malfunction detected.	AV communication circuits between AV control unit and TCU. Refer to Diagnosis Procedure.
Head unit ⇔ Meter	Combination meter AV communication connection malfunction detected.	AV communication circuits between AV control unit and combination meter. Refer to Diagnosis Procedure.

Area with yellow connection lines

Description

Possible malfunction location / Action to take

Head unit ⇔ TCU

TCU AV communication connection malfunction detected.

AV communication circuits between AV control unit and TCU.

Refer to Diagnosis Procedure.

Head unit ⇔ Meter

Combination meter AV communication connection malfunction detected.

AV communication circuits between AV control unit and combination meter.

Refer to Diagnosis Procedure.

A Connecting Cable Between Units Is Displayed In Yellow (Head Unit)

Area with yellow connection lines	Description	Possible malfunction location / Action to take
Head Unit ⇔ Amplifier	Internal amplifier malfunction detected.	Replace the AV control unit. Refer to Removal and Installation.
Head Unit ⇔ Conn Modules	Internal Bluetooth^® module malfunction detected. Internal WiFi module malfunction detected.	Replace the AV control unit. Refer to Removal and Installation.
Head Unit ⇔ Antenna	Window antenna connection malfunction detected. Satellite antenna connection malfunction detected.	Window or satellite antenna disconnected. Refer to Antenna and Antenna Feeder (window antenna) or Diagnosis Procedure (satellite antenna).
Head Unit ⇔ Speaker	Speaker connection malfunction detected.	Speaker disconnected. Refer to: Diagnosis Procedure, Diagnosis Procedure, DTC Diagnosis Procedure or DTC Diagnosis Procedure (front tweeter). Diagnosis Procedure or Diagnosis Procedure (front door speaker). Diagnosis Procedure or Diagnosis Procedure (rear speaker).
Head Unit ⇔ Microphone	Microphone connection malfunction detected.	Microphone disconnected. Refer to Diagnosis Procedure.
Head unit ⇔ USB	USB harness for front auxiliary input jacks control unit connection malfunction detected. AUX harness for front auxiliary input jacks connection malfunction detected.	Refer to Diagnosis Procedure.
Head Unit ⇔ FAN	Internal fan malfunction detected.	Replace the AV control unit. Refer to Removal and Installation.

CONFIRMATION/ADJUSTMENT MODE

Start the diagnosis function and select “Confirmation/Adjustment”. The confirmation/adjustment mode indicates where each item can be checked or adjusted.
Select each switch on the “Confirmation/Adjustment Mode” screen to display the relevant trouble diagnosis screen. Touch the “Back” to return to the initial Confirmation/Adjustment Mode screen.

Display Diagnosis

Confirmation of the AV control unit screen operation.

Nissan Sentra Vehicle Signals

A comparison check can be made of each actual vehicle signal and the signals recognized by the system.

Navigation

Displayed, but not used.

Error Location Display

Results of the error occurrence are represented by the time the error occurred.

AV COMM Diagnosis

AV COMM Monitor

Displays the communication status between AV control unit (master unit) and each unit.
The error counter displays “OK” if any malfunction was not detected in the past and displays “0” if a malfunction is detected. It increases by 1 if the condition is normal at the next ignition switch ON cycle. The upper limit of the counter is 39.
The error counter is erased if “Reset” is pressed.

Camera

Item	Description
Correct Draw Line of Rear view Camera	The guiding lines in the rear view monitor can be adjusted.
Alter/Confirm Configuration	Displays the current configuration data.
Reset Configuration	Initializes the camera system configuration.

Delete Unit Connection Log

Deletes error records from the AV control unit memory.

Initialize Settings

Initializes the AV control unit memory.

GPS Time Set

Displayed, but not used.

Version Information

Version information of the components of the AV control unit system are displayed.

Software Update

Version of the AV control unit software can be update.

### Speaker Test

Two test tones, 100Hz and 4KHz, can be generated to each speaker.

Radio Tuner

Displays FM and AM monitor information.

SXM

Displays SXM monitor information.

Consult Function

CONSULT Function

CONSULT FUNCTIONS

CONSULT performs the following functions via communication with the AV Control unit:

Diagnosis Mode	CGW Status			Description
Diagnosis Mode	Restricted Mode	Diag Test Mode	Open Mode	Description
ECU Identification	Display	Display	Display	The AV control unit part number is displayed.
Self Diagnostic Result	Display	Display	Display	The AV control unit self diagnostic results are displayed.
CGW Information	Display	Display	Display	Display the current CGW mode Enables CGW to switch mode
Data Monitor	Display	Display	Display	The AV control unit input/output data is displayed in real time.
Work Support	Non-display	Non-display	Display	Save or write VIN information.
Configuration	Display	Display	Display	The Nissan Sentra vehicle specification can be read and saved. The vehicle specification can be written when replacing AV control unit.
CAN Diag Support Monitor*	Display	Display	Display	Note: The mode is indicated, but not monitored.
Network-DTC*	Display	Display	Display	Display network DTC which AV control unit memorizes when performing "Diagnosis (All System)".

*: Displays when performing "Diagnosis (All System)".

ECU IDENTIFICATION

The part number of AV control unit is displayed.

SELF DIAGNOSTIC RESULT

Refer to DTC Index.

CGW INFORMATION

Displays the diagnosis mode which a user can perform in Diag Test mode/Open Mode by switching the CGW status from Restricted mode to Diag Test Mode/Open Mode.

For the method of switching CAN Gateway status, refer to CONSULT Function.

DATA MONITOR

Note:

The following table includes information (items) inapplicable to this Nissan Sentra vehicle. For information (items) applicable to this vehicle, refer to CONSULT display items.

Monitor Item [Unit]	Description
Sunload sensor [On/Off]	Indicates sunload sensor signal received from A/C auto amp. on CAN communication line.
Parking brake [On/Off]	Indicates condition of parking brake signal for the AV control unit.
IGN SIG [On/Off]	Indicates condition of ignition signal.
Auto ACC [On/Off]	Indicates condition of auto ACC signal.
ACC [On/Off]	Indicates condition of ACC signal.
Aux IN 1 [Con/No con]	Indicates connection condition of Aux in jack.
Aux IN 2 [Con/No con]	Indicates connection condition of USB.
TCU mute signal [On/Off]	Indicates condition of mute signal received from TCU.
REV SIG [On/Off]	Indicates condition of reverse signal received from transmission range switch.
ILLUM SIG [On/Off]	Indicates condition of illumination signal for the AV control unit.
Illumination Control[On/Off]	Indicates condition of illumination control signal for the AV control unit.

WORK SUPPORT

Test item	Description
SAVE VIN DATA	Allows the reading of VIN data written in AV control unit to store the specification in CONSULT.
WRITE VIN (SAVED DATA)	Allows the writing of the VIN data stored in CONSULT into the AV control unit.
WRITE VIN (MANUAL INPUT)	Allows the writing of the VIN data into the AV control unit by hand.

CONFIGURATION

Configuration has three functions as follows.

Function		Description
Read/Write Configuration	Before Replace ECU	Allows the reading of Nissan Sentra vehicle specification written in AV control unit to store the specification in CONSULT.
Read/Write Configuration	After Replace ECU	Allows the writing of the Nissan Sentra vehicle information stored in CONSULT into the AV control unit.
Manual Configuration		Allows the writing of the Nissan Sentra vehicle specification into the AV control unit by hand.

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Nissan Sentra B18 (2020-2025) Service Manual: Diagnosis System (av Control Unit)

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