Diagnostic Procedure
- STEP 1. Scan tool CAN bus diagnostics
Using scan tool MB991958, diagnose the CAN bus lines.
Q: Is the check result normal?
YES : Go to Step 3.
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?
YES : Go to Step 3.
NO : This diagnosis is complete.
- STEP 3. ACD proportioning valve single unit check
Measure the resistance of ACD proportioning valve.
Standard value: 3.7 ± 0.3 Ω
Q: Is the check result normal?
YES : Go to Step 4.
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-46, D-11, F-16
Q: Is the check result normal?
YES : Go to Step 5.
NO : Repair the defective connector. Then go to Step 8.
- STEP 5. Check the wiring harness between C-46 AWC-ECU connector terminal No. 1 and F-16 proportioning valve (for ACD) connector terminal No. 3 and between F-16 proportioning valve (for ACD) connector terminal No. 2 and body ground.
Check the output line and ground line for open or short circuit.
Q: Is the check result normal?
YES : Go to Step 6.
NO : Repair the wiring harness. Then go to Step 8.
- STEP 6. Scan tool service data
Item 92: ACD proportional valve indicator current (Refer to SERVICE DATA REFERENCE TABLE .)
Q: Is the check result normal?
YES : Go to Step 7.
NO : Replace the AWC-ECU.(Refer to AWC-ECU .) Then go to Step 7.
- STEP 7. Check whether the DTC is reset.
Q: Is DTC No. C161C set?
YES : Replace the AWC-ECU.(Refer to AWC-ECU .) Then go to Step 8.
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?
YES : Return to Step 1.
NO : This diagnosis is complete.