DTC B1B03: Driver's Air Bag Module (1st squib) System (Short Circuit Between Squib Circuit Terminals); DTC B1B07: Driver's Air Bag Module (2nd squib) System (Short Circuit Between Squib Circuit Terminals): 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)
• MB991865: Dummy resistor
• MB991866: Resister harness

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 "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 SRS-ECU connector C-122, driver's air bag module connector C-207 and clock spring connector C-208. 
   1. Disconnect the negative battery terminal.
   2. While pressing the part A in the illustration of the C-122 SRS-ECU harness side connector, turn the lock lever toward the arrow direction to release the lock lever. Then, disconnect the connector and reconnect it.
      Fig 2: Turning Lock Lever

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   3. Disconnect the C-208 clock spring connector and C-207 driver's air bag module connector, and then reconnect them. Disconnect C-207 driver's air bag module connector while sliding its outer housing toward the arrow direction in the illustration.
   4. Connect the negative battery terminal.
   5. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

   Q: Is DTC B1B03 < 1st squib > or B1B07 < 2nd squib > set? 

   • YES:  Go to Step 4.
   • NO:  The procedure is complete. It is assumed that DTC B1B03 < 1st squib > or B1B07 < 2nd squib > set because connector C-122, C-207 or C-208 was engaged improperly.
     Fig 3: Sliding Outer Housing Of Driver'S Air Bag Module Connector C-207

     Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
4. STEP 4. Check the driver's air bag module. 
   1. Disconnect the negative battery terminal.
   2. Slide the outer housing of the clock spring side of driver's air bag module connector C-207 in the arrow direction shown, and disconnect the connector.
      Fig 4: Sliding Outer Housing Of Driver'S Air Bag Module Connector C-207

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      Fig 5: Connecting Special Tool MB991865 To Special Tool MB991866

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   3. Connect special tool MB991865 to special tool MB991866.
      CAUTION: Do not insert a probe into the terminal from its front side directly as the connector contact pressure may be weakened.
   4. Insert special tool MB991866 into clock spring side of driver's air bag module connector C-207 (terminal No. 1 and 2 < 1st squib > or No. 3 and 4 < 2nd squib >) by backprobing.
   5. Connect the negative battery terminal.
      CAUTION: Always DTC B1B06 is set when checking DTC B1B03. This is because the second side terminal is isolated when checking it. DTC B1B06 is set but this is not a fault. In addition, always DTC B1B02 is set when checking DTC B1B07 because the first side terminal is isolated.
   6. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

   Q: Is the checked DTC set? 

   • YES:  Go to Step 5.
   • NO:  Replace the driver's air bag module (Refer to DRIVER'S AIR BAG MODULE AND CLOCK SPRING < Except RALLIART >  ) < Except RALLIART >, (Refer to DRIVER'S AIR BAG MODULE AND CLOCK SPRING < RALLIART >  ) < RALLIART >. Then go to  Step 8.
5. STEP 5. Check the clock spring. 
   1. Disconnect the negative battery terminal.
   2. Disconnect the clock spring connector C-208.
   3. Connect special tool MB991865 to special tool MB991866.
      CAUTION: Do not insert a probe into the terminal from C-208 harness side connector front side directly, as the connector contact pressure may be weakened.
   4. Insert special tool MB991866 into clock spring harness side connector C-208 (terminal No. 3 and 4 < 1st squib > or No. 1 and 2 < 2nd squib >) by backprobing.
   5. Connect the negative battery terminal.
      CAUTION: Always DTC B1B06 is set when checking DTC B1B03. This is because the second side terminal is isolated when checking it. DTC B1B06 is set but this is not a fault. In addition, always DTC B1B02 is set when checking DTC B1B07 because the first side terminal is isolated.
   6. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

   Q: Is the checked DTC set? 

   • YES:  Go to Step 6.
   • NO:  Replace the clock spring (Refer to DRIVER'S AIR BAG MODULE AND CLOCK SPRING < Except RALLIART >  ) < Except RALLIART >, (Refer to DRIVER'S AIR BAG MODULE AND CLOCK SPRING < RALLIART >  ) < RALLIART >. Then go to  Step 8.
     Fig 6: Connecting Special Tool MB991865 To Special Tool MB991866

     Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
6. STEP 6. Check the driver's air bag module circuit. Measure the resistance at SRS-ECU connector C-122. 
   1. Disconnect the negative battery terminal.
   2. While pushing the part "A" indicated in the illustration of the harness side connector, turn the lock lever to the direction of the arrow to release the lock lever, and disconnect the C-122 SRS-ECU connector.
      WARNING: To prevent the air bag from deploying unintentionally, disconnect clock spring connector C-208 to short the squib circuit.
   3. Disconnect clock spring connector C-208.
      CAUTION: Insert an insulator such as a cable tie to a depth of 4mm (0.16 inch) or more, otherwise the short spring will not be released.
   4. Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] between terminals 5, 6 < 1st squib > or 9, 10 < 2nd squib > and the short spring to release the short spring.
      Fig 7: Turning Lock Lever

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      Fig 8: Inserting Cable Tie Wide Between Terminals 5, 6 (1st Squib) And Short Spring

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
      Fig 9: Inserting Cable Tie Wide Between Terminals 9, 10 (2nd Squib) And Short Spring

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
   5. Check for continuity between C-122 harness side connector terminals 5 and 6 < 1st squib > or 9 and 10 < 2nd squib >. It should be open circuit.

   Q: Is it open circuit? 

   • YES:  Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC B1B03 < 1st squib > or B1B07 < 2nd squib > set, replace the SRS-ECU (Refer to SRS CONTROL UNIT (SRS-ECU)  ). Then go to  Step 8.
   • NO:  Go to Step 7.
     Fig 10: Checking Continuity Between C-122 Harness Side Connector Terminals 5 And 6 (1st Squib)

     Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
     Fig 11: Checking Continuity Between C-122 Harness Side Connector Terminals 9 And 10 (2nd Squib)

     Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
7. STEP 7. Check the harness for short circuit between the harness wire and wire. 
   • SRS-ECU connector C-122 (terminal No. 5 and 6) and clock spring connector C-208 (terminal No. 4 and 3) < 1st squib >.
   • SRS-ECU connector C-122 (terminal No. 9 and 10) and clock spring connector C-208 (terminal No. 1 and 2) < 2nd squib >.

   Q: the check result normal? 

   • YES:  Go to Step 8.
   • NO:  Repair the harness wires between SRS-ECU connector C-122 and clock spring connector C-208. Then go to Step 8.
8. STEP 8. 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 DTC B1B03 < 1st squib > or B1B07 < 2nd squib > set? 

   • YES:  Return to  Step 1.
   • NO:  The procedure is complete.