Inspection Procedure A-1: Communication with the M.U.T.-III is not possible.

caution

Whenever the ECU is replaced, ensure that the power supply circuit, the earthing circuit and the communication circuit are normal.

COMMENTS ON TROUBLE SYMPTOM

It is suspected that the power supply circuit to the ETACS-ECU is defective, or the wiring harness between the diagnosis connector and the ETACS-ECU or their connector(s) is damaged.

note

If the wiring harness between the ETACS-ECU and body earth is defective, also check C-219 ETACS-ECU connector terminal No.3, and repair if necessary.

POSSIBLE CAUSES

Malfunction of the ETACS-ECU
Damaged harness wires and connectors

DIAGNOSTIC PROCEDURE

Step 1. Check that the M.U.T.-III communicates with the other systems.

Use the M.U.T.-III to confirm that it communicates with the engine-ECU.

Q. Is the check result normal?

	Go to Step 2.

	Diagnose the system, which cannot communicate with the M.U.T.-III.

Step 2. Check that the M.U.T.-III can communicate with the system.

When the ignition switch is turned ON, check if the M.U.T.-III can communicate with the system.

Q. Is the check result normal?

	Refer to Inspection Procedure A-2 "When the ignition switch is at the LOCK (OFF) position, the functions do not work normally. Check the battery power supply circuit to the ETACS-ECU ."

	Go to Step 3.

Step 3. Connector check: C-221 ETACS-ECU connector

Q. Is the check result normal?

Go to Step 4.

Repair the defective connector.

Step 4. Resistance measurement at the C-221 ETACS-ECU connector.

(1)Disconnect the connector, and measure at the junction block side.

(2)Resistance between C-221 ETACS-ECU connector terminal No.56 and body earth
OK: 2 Ω or less

Q. Is the check result normal?

Go to Step 6.

Go to Step 5.

Step 5. Check the wiring harness between C-221 ETACS-ECU connector terminal No.56 and body earth.

Check the earth wires for open circuit.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction

Repair the wiring harness.

Step 6. Connector check: C-126 diagnosis connector

Q. Is the check result normal?

Go to Step 7.

Repair the defective connector.

Step 7. Check the wiring harness from C-221 ETACS-ECU connector terminal Nos. 51 and 67 to C-126 diagnosis connector terminal Nos. 9 and 1.

Check the communication lines for open circuit.

Q. Is the check result normal?

Go to Step 8.

Repair the wiring harness.

Step 8. Retest the system.

Check whether the communication with the M.U.T.-III is possible.

Q. Is the check result normal?

	The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

	Replace the ETACS-ECU.