Inspection Procedure 3

Inspection Procedure 3: Abnormality in KOS-ECU 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 KOS-ECU does not work at all or if the KOS-ECU cannot communicate with the scan tool, the KOS-ECU power supply or the ground circuit may be defective.

TROUBLESHOOTING HINTS

- Damaged wiring harness and connectors
- Malfunction of KOS-ECU

DIAGNOSIS

Required Special Tools:

- MB992006: Extra fine probe
- MB991223: Harness set

STEP 1. Check KOS-ECU connector C-05 and ETACS-ECU connector C-317 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is the KOS-ECU connector C-05 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 the KOS-ECU connector C-05
(terminal No.38, 39) and the ETACS-ECU connector C-317 (terminal No.10, 5) for open circuit.

(1)Disconnect KOS-ECU connector C-05 and ETACS-ECU connector C-317, and check the wiring harness.





(2)Check the wiring harness between KOS-ECU connector C-05 (terminal No.38) and ETACS-ECU connector C-317 (terminal No.10).
OK: Continuity exists (2ohms or less)






(3)Check the wiring harness between KOS-ECU connector C-05 (terminal No.39) and ETACS-ECU connector C-317 (terminal No.5).
OK: Continuity exists (2ohms or less)

Q. Is the wiring harness between KOS-ECU connector C-05 (terminal No.38, 39) and the ETACS-ECU connector C-317 (terminal No.10, 5) in good condition?

YES Go to Step 3.

NO Repair the wiring harness between KOS-ECU connector C-05 (terminal No.38, 39) and the ETACS-ECU connector C-317 (terminal No.10, 5).

STEP 3. Check the wiring harness between the KOS-ECU connector C-05
(terminal No.38, 39) and the ground for short circuit.

(1)Disconnect KOS-ECU connector C-05, and check the wiring harness.





(2)Check the wiring harness between KOS-ECU connector C-05 (terminal No.38) and ground.
OK: No continuity






(3)Check the wiring harness between KOS-ECU connector C-05 (terminal No.39) and ground.
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.

OK: No continuity

Q. Is the wiring harness between KOS-ECU connector C-05 (terminal No.38, 39) and the ground in good condition?

YES Go to Step 4.

NO Repair the wiring harness between KOS-ECU connector C-05 (terminal No.38, 39) and the ground.

STEP 4. Check the wiring harness between the KOS-ECU connector C-05 and the ground for open circuit.

(1)Disconnect KOS-ECU connector C-05, and check the wiring harness.





(2)Check the wiring harness between KOS-ECU connector C-05 (terminal No.14) and ground.
OK: Continuity exists (2ohms or less)

Q. Is the wiring harness between KOS-ECU connector C-05 and the ground in good condition?

YES Go to Step 5.

NO Repair the wiring harness between KOS-ECU connector C-07 and ground.

STEP 5. Retest the system

Q. Does the abnormality in KOS-ECU power supply and ground circuits in good condition?

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