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Nissan Sentra Service Manual: P1574 ASCD Vehicle speed sensor

Nissan Sentra Service Manual / Engine / Engine control system / Dtc/circuit diagnosis / P1574 ASCD Vehicle speed sensor

Description

The ECM receives two vehicle speed sensor signals via CAN communication line. One is sent from combination meter, and the other is from TCM (Transmission control module). The ECM uses these signals for ASCD control. Refer to EC-51, "AUTOMATIC SPEED CONTROL DEVICE (ASCD) : System Description" for ASCD functions.

DTC Logic

DTC DETECTION LOGIC

NOTE:

DTC No.

 CONSULT screen terms (Trouble diagnosis content)

 DTC detecting condition

 Possible cause
P1574 ASCD VHL SPD SEN (ASCD VHL SPD SEN) ECM detects a difference between two vehicle speed signals is out of the specified range.
  • Harness or connectors (CAN communication line is open or shorted.)
  • ABS actuator and electric unit (control unit)
  • TCM
  • ECM

DTC CONFIRMATION PROCEDURE

1.PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test.

  1. Turn ignition switch OFF and wait at least 10 seconds.
  2. Turn ignition switch ON.
  3. Turn ignition switch OFF and wait at least 10 seconds.

>> GO TO 2.

2.PERFORM DTC CONFIRMATION PROCEDURE

  1. Start engine.
  2. Drive the vehicle at more than 40 km/h (25 MPH).

CAUTION:

Always drive vehicle at a safe speed.

NOTE:

This procedure may be conducted with the drive wheels lifted in the shop or by driving the vehicle.

If a road test is expected to be easier, it is unnecessary to lift the vehicle.

  1. Check DTC.

Is DTC detected? YES >> Proceed to EC-397, "Diagnosis Procedure".

NO >> INSPECTION END

Diagnosis Procedure

1.CHECK DTC WITH TCM

Check DTC with TCM. Refer to TM-108, "CONSULT Function".

Is DTC detected?

NO >> GO TO 2.

YES >> Perform trouble shooting relevant to DTC indicated.

2.CHECK DTC WITH “ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)”

Check DTC with ABS actuator and electric unit (control unit). Refer to BRC-31, "CONSULT Function (ABS)".

Is DTC detected? NO >> INSPECTION END

YES >> Perform trouble shooting relevant to DTC indicated.

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