DTC B1B8C: Driver Seat Slide Sensor Circuit Performance: 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  ."
   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? 

   • YES:  Go to Step 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. Recheck for diagnostic trouble code. 

   Check again if the DTC is set.

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

   Q: Is the DTC set? 

   • YES:  Go to Step 3.
   • NO:  There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
3. STEP 3. Check the occupant classification-ECU connector D-35-2, front seat assembly connector D-35 and seat slide sensor connector D-28 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Is the occupant classification-ECU connector D-35-2, front seat assembly connector D-35 and seat slide sensor connector D-28 in good condition? 

   • YES:  Go to Step 4.
   • NO:  Replace the component(s) (Refer to HARNESS CONNECTOR INSPECTION ).
4. STEP 4. Check the harness for open circuit between occupant classification-ECU connector D-35-2 (terminal No. 27 and 29) and the seat slide sensor connector D-28 (terminal No. 2 and 1). 
   1. Disconnect occupant classification-ECU connector D-35-2 and seat slide sensor connector D-28.
      CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.
   2. Check for continuity between the following terminals. It should be less than 2 ohms.
      • Occupant classification-ECU connector D-35-2 (terminal No. 27) and the seat slide sensor connector D-28 (terminal No. 2)
      • Occupant classification-ECU connector D-35-2 (terminal No. 29) and the seat slide sensor connector D-28 (terminal No. 1)

   Q: Does continuity exist? 

   • YES:  Go to Step 5.
   • NO:  Repair the harness wires between occupant classification-ECU connector D-35-2 and seat slide sensor connector D-28.
     Fig 2: Checking Continuity Between Occupant Classification-ECU Connector D-35-2 (Terminal 27) And Seat Slide Sensor Connector D-28 (Terminal 2)

     Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
5. STEP 5. Check the seat slide sensor circuit. Measure the resistance at occupant classification-ECU connector D-35-2. 
   1. Disconnect occupant classification connector-ECU connector D-35-2.
   2. Disconnect seat slide sensor connector D-28.
      CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.
   3. Check for continuity between D-35-2 harness side connector terminals 27 and 29.

      It should be open circuit.

   Q: Is it open circuit? 

   • YES:  Go to Step 6.
   • NO:  Repair the harness wires between occupant classification-ECU connector D-35-2 and seat slide sensor connector D-28.
     Fig 3: Checking Continuity Between D-35-2 Harness Side Connector Terminals 27 And 29

     Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
6. STEP 6. Check the harness for open circuit between occupant classification-ECU connector D-35-2. 
   1. Disconnect occupant classification-ECU connector D-35-2 and seat slide sensor connector D-28.
      CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.
   2. Check for continuity between D-35-2 Occupant classification-ECU connector terminals No. 27, 29 and body ground.

      It should be open circuit.

   Q: Is it open circuit? 

   • YES:  Go to Step 7
   • NO:  Repair the harness wires between occupant classification-ECU connector D-35-2 and seat slide sensor connector D-28.
     Fig 4: Checking Continuity Between D-35-2 Occupant Classification-ECU Connector Terminals 27, 29 And Body Ground

     Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
7. STEP 7. Recheck for diagnostic trouble code. 

   Check again if the DTC is set to the occupant classification-ECU.

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

   Q: Is the DTC set? 

   • YES:  Replace the front seat cushion frame (LH) (Refer to DISASSEMBLY AND ASSEMBLY ) < Except RALLIART > or replace the slide adjuster (LH) (Refer to DISASSEMBLY AND ASSEMBLY ) < RALLIART >. Then go to Step 8.
   • NO:  There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
8. STEP 8. Recheck for diagnostic trouble code. 

   Check again if the DTC is set to the occupant classification-ECU.

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

   Q: Is the DTC set? 

   • YES:  Replace the front seat cushion frame (RH) (Refer to DISASSEMBLY AND ASSEMBLY ) < Except RALLIART > or replace the slide adjuster (RH) (Refer to DISASSEMBLY AND ASSEMBLY ) < RALLIART >.
   • NO:  There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).