Inspection Procedure 6: Check the hands-free module power supply circuit: Diagnosis

Required Special Tools:

• MB991223: Harness Set
• MB992006: Extra Fine Probe

1. STEP 1. Check hands-free module connector C-121 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Is hands-free module connector C-121 in good condition? 

   YES:  Go to Step 2.

   NO:  Repair or replace the damaged component(s). Refer to HARNESS CONNECTOR INSPECTION .

2. STEP 2. Check the ground circuit to the hands-free module. Measure the resistance at hands-free module connector C-121. 
   1. Disconnect hands-free module connector C-121, and measure at the wiring harness side.
   2. Measure the resistance value between terminal 15 and ground.

   OK: The resistance should be 2 ohms or less. 

   Q: Is the measured resistance 2 ohms or less? 

   YES:  Go to  STEP 4.

   NO:  Go to Step 3.

   Fig 1: Measuring Resistance Between Terminal 15 And Ground

   Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
3. STEP 3. Check the wiring harness between hands-free module connector C-121 (terminal 15) and ground. 

   Q: Is the wiring harness between hands-free module connector C-121 (terminal 15) and ground in good condition? 

   YES:  Replace the hands-free module. The system should communicate with the hands-free module normally.

   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.

4. STEP 4. Check the wiring harness between hands-free module connector C-121 (terminal 15) and fusible link (36). 
   NOTE: Also check ETACS-ECU connectors C-307 and C-317 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If ETACS-ECU connector C-307 or C-317 is damaged, repair or replace the damaged component(s) as described in HARNESS CONNECTOR INSPECTION .

   Q: Is the wiring harness between hands-free module connector C-121 (terminal 15) and fusible link (36) in good condition? 

   YES:  Replace the hands-free module. The system should communicate with the hands-free module normally.

   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.