DTC 71: Side-Airbag Module (RH) (Squib) System Fault 1 (Short Circuit between Terminals of the Squib Circuit): Diagnosis

Required Special Tools: 

• MB991958: Scan Tool (MUT-III Sub Assembly)
  • MB991824: Vehicle Communication Interface (V.C.I.)
  • MB991827: MUT-III USB Cable
  • MB991911: MUT-III Main Harness B (Vehicles without CAN communication system)
• MB991865: Dummy resister
• MB991866: Resister harness

1. STEP 1. Using scan tool MB991958, read the diagnostic trouble code 

   Q: Is DTC 34 set? 

   • YES:  Go to Step 2.
   • NO:  Go to  Step 3.
     Fig 1: Connecting Scan Tool To Data Link Connector

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2. STEP 2. Check SRS-ECU connector C-13. 

   Q: Is the connector correctly engaged? 

   • YES:  Go to Step 3.
   • NO:  Engage the connector correctly. Then go to  Step 7.
     Fig 2: Identifying Harness SRS-ECU Connector C-13

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3. STEP 3. Check SRS-ECU connector C-13 and side-airbag module (RH) connector D-27 (Using scan tool MB991958, read the diagnostic trouble code). 
   1. Disconnect the negative battery terminal.
   2. Disconnect connectors C-13 and D-27, and then reconnect them.
   3. Connect the negative battery terminal.
   4. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

   Q: Is DTC 71 out put? 

   • YES:  Go to Step 4.
   • NO:  The procedure is complete. It is assumed that DTC 71 set as connector C-13 or D-27 was engaged improperly.
     Fig 3: Identifying Harness Connector C-13

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     Fig 4: Identifying Harness Connector D-27

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4. STEP 4. Check the side-airbag module (RH) (Using scan tool MB991958, read the diagnostic trouble code). 
   1. Disconnect the negative battery terminal.
   2. Disconnect the side-airbag module (RH) connector D-27.
      Fig 5: Identifying Harness Connector D-27

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   3. Connect special tool MB991865 to special tool MB991866.
      CAUTION: Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.
   4. Insert special tool MB991866 into the D-27 harness connector by backprobing.
   5. Connect the negative battery terminal.
   6. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.
      Fig 6: Checking Harness Connector D-27

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   Q: Is DTC 71 set? 

   • YES:  Go to Step 5.
   • NO:  Replace the seat back assembly of the front seat (RH) (Refer to FRONT SEAT ASSEMBLY .) Then go to  Step 7.
5. STEP 5. Check the side-airbag module (RH) circuit at the SRS-ECU connector C-13. 
   1. Disconnect SRS-ECU connector C-13.
      Fig 7: Identifying Harness SRS-ECU Connector C-13

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      DANGER 

      To prevents the air bag from deploying unintentionally, disconnect the side-airbag module (RH) connector D-27 to short the squib circuit. 

   2. Disconnect side-airbag module connector D-27.
      Fig 8: Identifying Side-Airbag Module Connector D-27

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      CAUTION: Insert an insulator such as a cable tie to a depth of 4mm (0.16 inch) or more, otherwise the short bar will not be released.
   3. Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] between terminals 23, 24 and the short spring to release the short spring.
   4. Measure at the wiring harness side.
      Fig 9: Identifying Harness Connector C-13

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      CAUTION: Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.
   5. Check for continuity between C-13 harness connector terminals 23 and 24.

      It should be open circuit.

   Q: Does continuity exist? 

   • YES:  Go to Step 6.
   • NO:  Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC 71 sets, replace the SRS-ECU (Refer to SRS CONTROL UNIT (SRS-ECU)  .) Then go to  Step 7.
     Fig 10: Checking Continuity Between C-13 Harness Connector Terminals 23 And 24

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6. STEP 6. Check the harness wires for short circuit between SRS-ECU connector C-13 (terminal No.23 and 24) and side-airbag module (RH) connector D-27 (terminal No.1 and 2) 

   Q: Are the harness wires between SRS-ECU connector C-13 (terminal No.23 and 24) and side-airbag module (RH) connector D-27 (terminal No.1 and 2) in good condition? 

   • YES:  Go to Step 7.
   • NO:  Repair the harness wires between SRS-ECU connector C-13 and side-airbag module (RH) connector D-27. Then go to Step 7.
     Fig 11: Identifying Harness SRS-ECU Connector C-13

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     Fig 12: Identifying Harness Connector D-27

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7. STEP 7. Recheck for diagnostic trouble code. 

   Q: Is DTC 71 set? 

   • YES:  Return to  Step 1.
   • NO:  The procedure is complete (If no malfunctions are found in all steps, an intermittent malfunction is suspected. Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION .)