Inspection Procedure 4

Inspection Procedure 4: Abnormality in WCM power supply and ground circuits.

CAUTION:
Before replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.


















TECHNICAL DESCRIPTION (COMMENT)

If the WCM does not work at all or if the WCM cannot communicate with the scan tool, the WCM power supply or the ground circuit may be defective.

TROUBLESHOOTING HINTS

- Damaged wiring harness and connectors
- Malfunction of the WCM

DIAGNOSIS

Required Special Tools:

- MB992006: Extra fine probe
- MB991223: Harness set

STEP 1. Check WCM connector C-07 and ETACS-ECU connector C-317 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is the WCM connector C-07 and ETACS-ECU connector C-317 in good condition?

YES Go to Step 2.
NO Repair the defective connector.
STEP 2. Check the wiring harness between WCM connector C-07 (terminal No.6, 9) and the ETACS-ECU connector C-317 (terminal No.10, 5) for open circuit.

(1)Disconnect WCM connector C-07 and ETACS-ECU connector C-317, and check the wiring harness.





(2)Check the wiring harness between WCM connector C-07 (terminal No.6) and ETACS-ECU connector C-317 (terminal No.10).
OK: Continuity exists (2ohms or less)






(3)Check the wiring harness between WCM connector C-07 (terminal No.9) and ETACS-ECU connector C-317 (terminal No.5).
OK: Continuity exists (2ohms or less)
NOTE:
Also check joint connector (1) C-101 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If joint connector (1) C-101 is damaged, repair or replace the damaged component(s) as described in Harness Connector Inspection Harness Connector Inspection.

Q. Is the wiring harness between WCM connector C-07 and the ETACS-ECU connector C-317 in good condition?

YES Go to Step 3.

NO Repair the wiring harness between WCM connector C-07 (terminal No.6, 9) and ETACS-ECU connector C-317 (terminal No.10, 5).

STEP 3. Check the wiring harness between the WCM connector C-07 (terminal No.7) and the ground for open circuit.

(1)Disconnect WCM connector C-07, and check the wiring harness.





(2)Check the wiring harness between WCM connector C-07 (terminal No.7) and ground.
OK: Continuity exists (2ohms or less)

Q. Is the wiring harness between WCM connector C-07 and the ground in good condition?

YES Go to Step 4.

NO Repair the wiring harness between WCM connector C-07 (terminal No.7) and ground.

STEP 4. Retest the system

Q. Does the abnormality in WCM power supply and ground circuits in good condition?

YES The trouble can be an intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Replace WCM and register the ID codes (Refer to ID registration procedure manual - ID codes registration judgement table).