Code No. B1731: ENG ECU authentification timeout

caution

If diagnosis code No. B1731 is stored in the ETACS-ECU, diagnose the CAN bus lines.
Whenever the ECU is replaced, ensure that the input and output signal circuits are normal.

TROUBLE JUDGEMENT

If the ETACS-ECU cannot receive any signals from the engine-ECU, diagnosis code B1731 will be stored.

COMMENT ON TROUBLE SYMPTOM

Connector(s) or wiring harness in the CAN bus lines between the ETACS-ECU and the engine-ECU, the power supply system to the engine-ECU, the engine-ECU itself, or the ETACS-ECU itself may be defective.

note

Diagnosis code No.B1731 is always stored along with MPI system diagnosis code No.U0167.

PROBABLE CAUSES

Malfunction of engine-ECU
Malfunction of ETACS-ECU
Damaged harness wires and connectors

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics.

Use the M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?

	Go to Step 2.

	Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting). Repair the CAN bus line and go to Step 3.

STEP 2. Check whether the diagnosis code is stored again.

Check again if the diagnosis code is stored.

(1)Turn the ignition switch to the "LOCK" (OFF) position once, and then turn it to the ON position again.

(2)Check that diagnosis code No.B1731 is not stored as a current trouble.

Q. Is diagnosis code No.B1731 stored?

	Replace the ETACS-ECU. After registering the ID codes, go to Step 3.

	The diagnosis is complete. If another diagnosis code is stored, refer to Diagnosis Code Chart .

STEP 3. Check whether the diagnosis code is stored again.

Recheck if the diagnosis code is stored.

(1)Turn the ignition switch to the "LOCK" (OFF) position once, and then turn it to the ON position again.

(2)Check that diagnosis code No.B1731 is not stored as a current trouble.

Q. Is diagnosis code No.B1731 stored?

	Replace the engine-ECU and resister the ID code.

	The diagnosis is complete. If another diagnosis code is stored, refer to Diagnosis Code Chart .