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





(1)
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.

Connect scan tool MB991958. Refer to "How to connect the Scan Tool (M.U.T.-III) Reading and Clearing Diagnostic Trouble Codes."
(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. CAN Bus Diagnostics Chart).

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] Manual Air Conditioning or Auto A/C Diagnosis Automatic Air Conditioning).
NO Go to Step 3.
STEP 3. Using scan tool MB991958, read the other system diagnostic trouble code.

Check if DTC U0164 is set to the combination meter.

Q. Is the DTC set?

YES Go to Step 4.
NO Go to Step 5.
STEP 4. 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 the A/C-ECU [vehicles with A/C] or heater control unit [vehicles without A/C].
NO The trouble can be an intermittent malfunction How to Cope With Intermittent Malfunctions).
STEP 5. 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 (Refer to ID registration procedure manual
- ID codes registration judgement table).
NO The trouble can be an intermittent malfunction How to Cope With Intermittent Malfunctions).