Code No.C1541 Locking fail safe relay on


caution
  • If the electric power steering-ECU sets diagnosis code No.C1541, diagnose the CAN bus lines. If there is any fault in the CAN bus lines, an incorrect diagnosis code may be set.
  • Whenever the ECU is replaced, ensure that the communication circuit is normal.


DIAGNOSIS CODE SET CONDITIONS

  • Although the fail-safe relay (power relay) is turned off, the system is energised and the microcomputer determines that the relay contact is short.
  • The fail-safe relay (power relay) is not turned off and the microcomputer determines that the relay contact is short.
    • Criteria for judging malfunction
    • Power supply voltage is more than 5 V and the difference between the ignition voltage and the power supply voltage is less than 3 V when the fail-safe relay is on.

PROBABLE CAUSES

  • Defective harness wire(s) or connector(s)
  • Defective motor of the steering gear and linkage assembly
  • Malfunction of the electric power steering-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the electric power steering-ECU connector B-105-1.


  • B-105-1 electric power steering-ECU connector
Check the connectors above for improper engagement, terminal damage or terminal drawn in the connector case.

Q. Is the check result normal?

Go to Step 2.

Repair the connector(s) or terminal(s).

STEP 2. Check the motor wires of the steering gear and linkage assembly wiring harness for short to earth.

Disconnect electric power steering-ECU connector B-105-1 and measure the resistance.

  • Resistance between electric power steering-ECU connector B-105-1 terminal 31 and body earth
  • Resistance between electric power steering-ECU connector B-105-1 terminal 32 and body earth
OK: Open circuit or more than 300 Ω

Q. Is the check result normal?

Replace the steering gear box and linkage assembly (Refer to ).

Go to Step 3.

STEP 3. Check whether the diagnosis code is reset.

caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Start the engine.
(6)Recheck whether diagnosis code C1531 is set.
(7)Turn the ignition switch to the "LOCK" (OFF) position.
(8)Disconnect M.U.T.-III.

Q. Is diagnosis code C1541 set?

Replace the electric power steering-ECU (Refer to ).

The malfunction is intermittent. Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .