Wireless Control Module (WCM)

DTC U0164: A/C-ECU [vehicles with A/C] or heater control unit [vehicles without A/C] CAN timeout

CAUTION:
- If DTC U0164 is set, be sure to diagnose the CAN bus line.
- When replacing the ECU, always check that the communication circuit is normal.

DIAGNOSTIC FUNCTION

If the signal from A/C-ECU [vehicles with A/C] or heater control unit [vehicles without A/C] cannot be received, the WCM sets DTC U0164.

TROUBLESHOOTING HINTS

- The CAN bus line may be defective.
- The A/C-ECU [vehicles with A/C] or heater control unit [vehicles without A/C] may be defective.
- The WCM may be defective.

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)

STEP 1. Using scan tool MB991958, diagnose the CAN bus line







CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Connect scan tool MB991958. Refer to "How to connect the Scan Tool (M.U.T.-III)". How To Connect The Scan Tool (M.U.T.-III)
2. Turn the ignition switch to the "ON" position.
3. Diagnose the CAN bus line.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the CAN bus line found to be normal?

YES: Go to Step 2.

NO: Repair the CAN bus line.

STEP 2. Using scan tool MB991958, read the A/C [vehicles with A/C] or heater [vehicles without A/C] diagnostic trouble code
Check if DTC is set to the A/C-ECU [vehicles with A/C] or heater control unit [vehicles without A/C].

Q: Is the DTC set?

YES: Troubleshoot the A/C [vehicles with A/C] or heater vehicles without A/C] (Refer to Manual A/C and heater Diagnosis Diagnostic Trouble Code Descriptions or Auto A/C Diagnosis). Diagnostic Trouble Code Descriptions

NO: Go to Step 3.

STEP 3. Recheck for diagnostic trouble code.
Check again if the DTC is set to the WCM.

1. Erase the DTC.
2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
3. Check if DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the DTC set?

YES: Replace WCM and register the ID codes.

NO: The trouble can be an intermittent malfunction.