VARIABLE GEAR RATIO STEERING SYSTEM, Diagnostic DTC:C15C7/78, C15C8/79

DTC Code DTC Name
C15C7/78 DC Motor Power Source Voltage Malfunction
C15C8/79 Power Supply Relay Failure

DESCRIPTION

The steering control ECU monitors PIG (motor power source voltage) and detects a malfunction in the power supply relay (located inside the steering control ECU).

If the steering control ECU detects a malfunction, it will turn on the master warning light, store these DTCs, and stop VGRS operation.

DTC Code Detection Condition Trouble Area
C15C7/78 The steering control ECU detects that the IG terminal voltage is between 9 and 16 V, and the PIG terminal voltage is less than 7 V or more than 18.5 V for 2.4 seconds

  • VGRS fuse

  • Wire harness or connector

  • Power source circuit

  • Steering control ECU
C15C8/79 The steering control ECU detects a malfunction in the power source relay or an open circuit

  • VGRS fuse

  • Wire harness or connector

  • Steering control ECU

WIRING DIAGRAM

A01GHKNE02

INSPECTION PROCEDURE

Tech Tips

The fault may be intermittent. Check harnesses and connectors thoroughly and retest.

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (STEERING CONTROL ECU - BODY GROUND)

    A01GKFYE01

    1. Disconnect the negative (-) terminal cable from the battery.

    2. Disconnect the A42 steering control ECU connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      A42-7 (PGND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK STEERING CONTROL ECU (POWER SOURCE CIRCUIT)


    1. A01GHKTE01

      Connect the negative (-) terminal cable to the battery.

    2. Record and clear the DTCs Click here.

    3. Start the engine.

    4. Measure the voltage of the steering control ECU.

      Standard voltage
      Tester Connection Condition Specified Condition

      A42-8 (PIG) -

      A42-7 (PGND)

      		 Always 9 to 16 V
      Result
      Result Proceed to
      9 to 16 V A
      Below 9 V B
      Above 16 V: 1UR-FSE Engine C
      Above 16 V: 1UR-FE Engine D

    B

    CHECK OR REPAIR HARNESS AND FUSE

    C

    CHECK OR REPAIR CHARGING SYSTEM Click here

    D

    CHECK OR REPAIR CHARGING SYSTEM Click here

    A

  3. CHECK DTC


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG) and turn the intelligent tester on.

    3. Check for DTCs Click here.

      Result
      Result Proceed to
      Neither C15C7/78 nor C15C8/79 is output OK
      C15C7/78 or C15C8/79 is output NG

    NG

    REPLACE STEERING CONTROL ECU Click here

    OK

    END