Diagnostic Procedure

WARNING: This page is about a different variant/trim than selected.

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. C161C set?
1. YES: Go to Step 3.
2. NO: This diagnosis is complete.
STEP 3. ACD proportioning valve check.
Measure the resistance of ACD proportioning valve.

Standard value: 3.7 ± 0.3 Ω

Q: Is the check result normal?
1. YES: Go to Step 4.
2. NO: Replace the hydraulic unit. (Refer to HYDRAULIC UNIT ). Then go to Step 8.
STEP 4. AWC-ECU connector, intermediate connector, proportioning valve (for ACD) connector check: C-51, D-11, F-28
Q: Is the check result normal?
1. YES: Go to Step 5.
2. NO: Repair the defective connector. Then go to Step 8.
STEP 5. Check the wiring harness between C-51 AWC-ECU connector terminal No. 1 and F-28 proportioning valve (for ACD) connector terminal No. 3 and between F-28 proportioning valve (for ACD) connector terminal No. 2 and body ground.
Check the power supply line for open or short circuit, and check the ground line for open circuit.

Q: Is the check result normal?
1. YES: Go to Step 6.
2. NO: Repair the wiring harness. Then go to Step 8.
STEP 6. Scan tool data list
Item 92: ACD proportion valve (Refer to DATA LIST REFERENCE TABLE ).

Q: Is the check result normal?
1. YES: Go to Step 7.
2. NO: Replace the AWC-ECU. (Refer to AWC-ECU ). Then go to Step 8.
STEP 7. Check whether the DTC is reset.
Q: Is DTC No. C161C set?
1. YES: Replace the AWC-ECU. (Refer to AWC-ECU ). Then go to Step 8.
2. NO: Intermittent malfunction. (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
STEP 8. Check whether the DTC is reset.
Q: Is DTC No. C161C set?
1. YES: Return to Step 1.
2. NO: This diagnosis is complete.