C161C

DTC C161C: ACD Proportioning Valve System (Malfunction)

ACD proportioning valve system





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 ACID 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. ACID proportioning valve 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-51, D-11, F-28

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-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 ACID) 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?
YES: Go to Step 6.
NO: Repair the wiring harness. Then go to Step 8.

STEP 6. Scan tool data list
Item 92: ACD proportion valve.

Q: Is the check result normal?
YES: Go to Step 7.
NO: Replace the AWC-ECU. Then go to Step 8.

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. (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.