If the EPS-ECU sets the diagnosis
code No. C1542, diagnose the CAN bus lines. If there is any fault in the CAN bus lines, an incorrect diagnosis
code may be set.
Before replacing ECU, ensure that the communication circuit is normal.
DIAGNOSIS CODE SET CONDITIONS
The diagnosis code No. C1542 is set when the condition below is satisfied.
Although the fail-safe relay (power relay) is turned on, the system is not
energised and the microcomputer determines that the relay contact is open.
The fail-safe relay (power relay) is not turned on and the microcomputer determines
that the relay contact is open.
CRITERIA FOR JUDGING MALFUNCTION
An abnormality is judged if the relay contact voltage of fail-safe relay is less than
4 V.
PROBABLE CAUSES
Defective wiring harness or connector in the power supply circuit to EPS-ECU
Malfunction of the EPS-ECU
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III diagnosis code
Recheck if the diagnosis code is set.
(1)Turn the electric motor switch to the "LOCK" (OFF) → "ON" position.
(2)Start the electric motor unit.
(3)Check if the diagnosis code No. C1542 and C1531 are set as the current trouble.
Q.
Are the diagnosis code No. C1542 set?
Go to Step 2.
Go to Step 4.
STEP 2. Measure the resistance at B-114-1 EPS-ECU connector.
(1)Disconnect the connector and measure at the wiring harness side.
(2)Measure the resistance between B-114-1 EPS-ECU connector terminal No. 2 and the
body earth. OK: Continuity exists. (300 Ω or more)
(3)Measure the resistance between B-114-1 EPS-ECU connector terminal No. 1 and the
body earth. OK: Continuity exists. (300 Ω or more)
Q.
Is the check result normal?
Go to Step 3.
Replace the steering gear & linkage assembly.
STEP 3. Diagnosis code recheck
Recheck if the diagnosis code is set.
(1)Turn the electric motor switch to the "LOCK" (OFF) → "ON" position.
(2)Check if the diagnosis code No. C1542 and C1531 are set as the current trouble.
Q.
Are the diagnosis code No. C1542 set?
Replace EPS-ECU.
Intermittent malfunction. (Refer to GROUP 00 - How to Cope with Intermittent
Malfunction .)
STEP 4. Measure the resistance at B-114-1 EPS-ECU connector.
(1)Disconnect the connector and measure at the wiring harness side.
(2)Measure the resistance between B-114-1 EPS-ECU connector terminal No. 1 and terminal
No. 2. OK: Continuity exists (2 Ω or less)
Q.
Is the check result normal?
Go to Step 5.
Repair the wiring harness and connector, or replace the steering gear box & linkage
assembly.
STEP 5. Diagnosis code recheck
Recheck if the diagnosis code is set.
(1)Turn the electric motor switch to the "LOCK" (OFF) → "ON" position.
(2)Start the electric motor unit.
(3)Check if the diagnosis code No. C1542 is set as a current trouble.
Q.
Is diagnosis code C1542 set?
Replace EPS-ECU.
Intermittent malfunction. (Refer to GROUP 00 - How to Cope with Intermittent
Malfunction .)
)
)
)
Go to Step 2.
Go to Step 4.
.)