Nissan Altima 2007-2012 Service Manual: ECU diagnosis

POWER STEERING CONTROL UNIT

Reference Value

TERMINAL LAYOUT

PHYSICAL VALUES

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

Wiring Diagram — ELECTRONICALLY CONTROLLED POWER STEERING SYSTEM

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:

    ECM branch line circuit
    Diagnosis Procedure INSPECTION PROCEDURE 1.CHECK CONNECTOR 1. Turn the ignition switch OFF. 2. Disconnect the battery cable from the negative terminal. 3. Check the following terminals and connectors for damage, bend and loose connection (unit side and connector side). - ECM - Harnes ...

    Power supply and ground circuit for front air control
    Description COMPONENT DESCRIPTION FRONT AIR CONTROL The front air control has a built-in microcomputer which processes information sent from various sensors needed for air conditioner operation. The air mix door motors, mode door motor, intake door motor, blower motor and compressor are then c ...

    DLC branch line circuit
    Diagnosis Procedure INSPECTION PROCEDURE 1.CHECK CONNECTOR 1. Turn the ignition switch OFF. 2. Disconnect the battery cable from the negative terminal. 3. Check the terminals and connectors of the data link connector for damage, bend and loose connection (connector side and harness side ...