DTC 15: Auto-cruise Control Switch System: Diagnosis

Required Special Tools:

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)
  • MB991824: V.C.I.
  • MB991827: M.U.T.-III USB Cable
  • MB991910: M.U.T.-III Main Harness A
• MB991223: Harness Set
• MB992006: Extra Fine Probe
• MB992110: Power Plant ECU Check Harness

1. STEP 1. Using scan tool MB991958, check the data list item 86: Main switch, item 92: Set switch, item 91: Resume switch and item 75: Cancel switch. 
   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 to the data link connector (Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III)  ).
   2. Turn the ignition switch to the "ON" position.
   3. Set scan tool MB991958 to data reading mode for auto-cruise control system (Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III)  ).
      • Item 86: Main switch.
        • When "ON/OFF" switch is at the "ON" position, the display on scan tool MB991958 should be "ON".
        • When "ON/OFF" switch is at the "OFF" position, the display on scan tool MB991958 should be "OFF".
      • Item 92: Set switch.
        • When "COAST/SET" switch is at the "ON" position, the display on scan tool MB991958 should be "ON".
        • When "COAST/SET" switch is at the "OFF" position, the display on scan tool MB991958 should be "OFF".
          Fig 1: Connecting Scan Tool MB991824 To Data Link Connector

          Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      • Item 91: Resume switch.
        • When "ACC/RES" switch is at the "ON" position, the display on scan tool MB991958 should be "ON".
        • When "ACC/RES" switch is at the "OFF" position, the display on scan tool MB991958 should be "OFF".
      • Item 75: Cancel switch.
        • When "CANCEL" switch is at the "ON" position, the display on scan tool MB991958 should be "ON".
        • When "CANCEL" switch is at the "OFF" position, the display on scan tool MB991958 should be "OFF".
   4. Turn the ignition switch to the "LOCK" (OFF) position.
   5. Disconnect scan tool MB991958.

   Q: Is the switch operating properly? 

   YES:  It can be assumed that this malfunction is intermittent (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).

   NO:  Go to Step 2.

2. STEP 2. Measure the power supply voltage at auto-cruise control switch connector C-201 by backprobing. 
   1. Remove the driver's air bag module (Refer to AIR BAG MODULES AND CLOCK SPRING ).
   2. Remove the auto-cruise control switch (Refer to AUTO-CRUISE CONTROL  ).
   3. Connect the negative (-) battery cable.
   4. Do not disconnect auto-cruise control switch connector C-201.
   5. Turn the ignition switch to the "ON" position.
   6. All auto-cruise control switch to the "OFF" position.
   7. Measure the power supply voltage between auto-cruise control switch connector C-201 terminal 3 and ground by backprobing.
   8. Turn the ignition switch to the "LOCK" (OFF) position.
      Fig 2: Measuring Voltage Between Auto-Cruise Control Switch Connector C-201 Terminal 3 And Ground

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

   Q: Is the measured voltage between 4.7 and 5.0 volts? 

   YES:  Go to  STEP 9.

   NO:  Go to Step 3.

3. STEP 3. Measure the power supply voltage at ECM connector B-11. 
   1. Disconnect all the connectors from the ECM.
   2. Connect special tool MB992110 between the ECM and the body-side harness connector.
   3. Turn the ignition switch to the "ON" position.
   4. All auto-cruise control switch to the "OFF" position.
      Fig 3: Connecting Special Tool MB992110 Between ECM And Body-Side Harness Connector

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.