Inspection Procedure 1: Power supply to the BSW-ECU (master) fails [Cannot communicate with BSW-ECU (master) using the scan tool (M.U.T.-III)]: Diagnosis

Required Special Tools: 

• MB991223: Harness Set
• MB992006: Extra Fine Probe

1. STEP 1. Connector check: BSW-ECU (master) connector G-25 

   Q: Is BSW-ECU (master) connector G-25 in good condition? 

   YES  : Go to Step 2.

   NO  : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.

2. STEP 2. Resistance measurement at BSW-ECU (master) connector G-25 (terminal No. 6) 
   1. Disconnect the connector, and measure at the wiring harness side.
   2. Measure the resistance between the BSW-ECU (master) connector G-25 (terminal No. 6) and body ground.

   OK: Continuity exists (2 ohms or less) 

   Q: Is the check result normal? 

   YES  : Go to Step 3.

   NO  : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

3. STEP 3. Voltage measurement at BSW-ECU (master) connector G-25 (terminal No. 1) 
   1. Disconnect the connector, and measure at the wiring harness side.
   2. Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
   3. Check the voltage between the BSW-ECU (master) connector G-25 (terminal No. 1) and body ground.

   OK: Battery positive voltage 

   Q: Is the check result normal? 

   YES  : Go to Step 4.

   NO  : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

4. STEP 4. Retest the system 

   Check if scan tool (M.U.T.-III) can communicate with the BSW-ECU (master).

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

   Connect scan tool (M.U.T.-III). Refer to DIAGNOSTIC FUNCTION  ."

   Q: Is the check result normal? 

   YES  : Intermittent malfunction is suspected (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).

   NO  : Replace the BSW-ECU (master).