Nissan Altima 2007-2012 Service Manual: ECU diagnosis


Reference Value



CAUTION: When using circuit tester or oscilloscope to measure voltage for inspection, be sure not to extend forcibly any connector terminals.


Fail Safe

EPS system

• EPS system enters the fail-safe mode (that allows the steering force to be controlled without impairing the drive ability) if any of the input/output signals to/from EPS system (power steering control unit) deviate from the standard.

NOTE: The system enters the fail-safe mode if the engine speed remains at 1,500 rpm or more for over 10 seconds while the vehicle is stopped. This is normal.

• The fail-safe function is canceled when a vehicle speed signal of 2 km/h (1.2 MPH) or more is inputted or the key switch is turned OFF→ ON. EPS system restores the normal operation at that time.

    Vehicle speed signal circuit
    Description • Combination meter sends vehicle speed signal to power steering control unit. Diagnosis Procedure 1.PERFORM COMBINATION METER SELF-DIAGNOSIS Perform combination meter self-diagno ...

    Symptom diagnosis
    UNBALANCE STEERING WHEEL TURNING FORCE (TORQUE VARIATION) Description • Hard steering when fully turning the steering wheel. • Light steering when driving at a high speed. Diagnosis Proce ...

    Other materials:

    Engine oil
    Inspection OIL LEVEL • Before starting the engine, check the oil level. If the engine is already started, stop it and allow 10 minutes before checking. • Check that the oil level is within the range on the dipstick. • If it is out of range, add oil as necessary. Refer to LU-9, " ...

    Power window system
    System Diagram FRONT POWER WINDOW LH ANTI-PINCH SYSTEM System Description MAIN POWER WINDOW AND DOOR LOCK/UNLOCK SWITCH INPUT/OUTPUT SIGNAL CHART POWER WINDOW OPERATION • Power window system is operable during the retained power operation timer after turning ignition switch ON and O ...

    Combination switch input circuit
    Diagnosis Procedure 1. CHECK INPUT 1 - 5 SYSTEM CIRCUIT FOR OPEN 1. Turn the ignition switch OFF. 2. Disconnect the BCM and combination switch. 3. Check continuity between BCM harness connector and combination switch harness connector. Does continuity exist? YES >> GO TO 2 NO ...