Inspection Procedure 1: Scan tool cannot communicate with WCM: 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.
      2. NO:  Repair the CAN bus line. (Refer to DIAGNOSIS ).
         Fig 1: Connecting Special Tool MB991910 To Data Link Connector

         Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
2. STEP 2. Check the power supply circuit and the ground circuit to WCM. 

   Refer to INSPECTION PROCEDURE 4 "ABNORMALITY IN WCM POWER SUPPLY AND GROUND CIRCUITS."  .

   Q: Are the power supply circuit and the ground circuit to WCM in good condition? 

   1. YES:  Go to Step 3.
   2. NO:  Repair the power supply circuit and the ground circuit to WCM.
3. STEP 3. Retest the system 

   Check if scan tool can communicate with WCM.

   Q: Does the scan tool cannot communicate with WCM in good condition? 

   1. YES:  The trouble can be an intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
   2. NO:  Replace WCM and register the ID codes. (Refer to ID CODES REGISTRATION JUDGMENT TABLE  .)