DTC U0164: A/C-ECU or heater control unit CAN timeout: 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)

1. 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)  ."
   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? 

   1. YES:  Go to STEP 2 below.
   2. NO:  Repair the CAN bus line (Refer to DIAGNOSIS ).
      Fig 1: Identifying Data Link Connector And Special Tools

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
2. STEP 2. Using scan tool MB991958, read the A/C-ECU diagnostic trouble code. 

   Check if DTC is stored in the A/C-ECU.

   Q: Is the DTC stored? 

   1. YES:  Troubleshoot the A/C-ECU (Refer to A/C DIAGNOSIS ).
   2. NO:  Go to STEP 3 below.
3. STEP 3. Using scan tool MB991958, read the combination meter diagnostic trouble code. 

   Check if the DTC U0164 is stored in the combination meter.

   Q: Is the DTC stored? 

   1. YES:  Go to STEP 4 below.
   2. NO:  Go to  Step 5.
4. STEP 4. Recheck for diagnostic trouble code. 

   Check again if the DTC is stored in the ETACS-ECU.

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

   Q: Is the DTC stored? 

   1. YES:  Replace the A/C-ECU.
   2. NO:  The trouble can be an intermittent malfunction such as a poor connection or open circuit in the CAN bus lines between the A/C-ECU and the ETACS-ECU (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
5. STEP 5. Recheck for diagnostic trouble code. 

   Check again if the DTC is stored in the ETACS-ECU.

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

   Q: Is the DTC stored? 

   1. YES:  Replace the ETACS-ECU.
   2. NO:  The trouble can be an intermittent malfunction such as a poor connection or open circuit in the CAN bus lines between the A/C-ECU and the ETACS-ECU (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).