C161C

DTC C161C: ACD Proportioning Valve System (Malfunction)














CAUTION
^ If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
^ Whenever the ECU is replaced, ensure that the CAN bus lines are normal.

OPERATION
AWC-ECU controls ACD proportioning valve.

DTC SET CONDITIONS
The code is set when the current monitor value of the ACD proportioning valve solenoid is determined to be abnormal.

PROBABLE CAUSES
^ ACD proportioning valve malfunction
^ Damaged harness wires and connectors
^ Malfunction of AWC-ECU

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. 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 ohms
Q: Is the check result normal?
YES: Go to Step 4.
NO: Replace the 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 (Data List Reference Table)
Q: Is the check result normal?
YES: Go to Step 7.
NO: Replace the 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. Then go to Step 8.
NO: 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.