Diagnostic Procedure

STEP 1. Scan tool CAN bus diagnostics
Using scan tool MB991958, diagnose the CAN bus lines.

Q: Is the check result normal?
1. YES: Go to Step 3.
2. NO: Repair the CAN bus lines. (Refer to TROUBLESHOOTING .) After repairing the CAN bus line, go to Step 2.
STEP 2. Check whether the DTC is reset.
Q: Is DTC No. C161D set?
1. YES: Go to Step 3.
2. NO: This diagnosis is complete.
STEP 3. Scan tool actuator test
OK: Operating sound of the electric pump can be heard.

Q: Is the check result normal?
1. YES: Go to Step 8.
2. NO: Go to Step 4.
STEP 4. Electric pump relay single unit check
Check the electric pump relay. (Refer to AWC SWITCH CHECK .)

Q: Is the check result normal?
1. YES: Go to Step 5.
2. NO: Replace the electric pump relay. (Refer to AWC-ECU .) Then go to Step 9.
STEP 5. Electric pump relay connector, AWC-ECU connector check: A-26X, C-46
Q: Is the check result normal?
1. YES: Go to Step 6.
2. NO: Repair the defective connector. Then go to Step 9.
STEP 6. Check the wiring harness between A-26X electric pump relay connector terminal No. 3 and C-46 AWC-ECU connector terminal No. 20.
Check the power supply line for short or open circuit.

Q: Is the check result normal?
1. YES: Go to Step 7.
2. NO: Check C-47 intermediate connector. When no problem is found, repair the wiring harness. Then go to Step 9.
STEP 7. Check the wiring harness between A-26X electric pump relay connector terminal No. 1 and body ground.
Check the ground line for open circuit.

Q: Is the check result normal?
1. YES: Go to Step 8.
2. NO: Repair the wiring harness. Then go to Step 9.
STEP 8. Check whether the DTC is reset.
Q: Is DTC No. C161D set?
1. YES: Replace the AWC-ECU. (Refer to AWC-ECU .) Then go to Step 9.
2. NO: Intermittent malfunction. (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION .)
STEP 9. Check whether the DTC is reset.
Q: Is DTC No. C161D set?
1. YES: Return to Step 1.
2. NO: This diagnosis is complete.