Inspection Procedure 3
Inspection Procedure 3: Abnormality In KOS-ECU Power Supply And Ground CircuitsCAUTION: Before replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
KOS-ECU Power Supply Circuit:
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 (2 ohms 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 (2 ohms 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
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 (2 ohms 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.
NO : Replace KOS-ECU and register the ID codes.