DTC B1440: Curtain Air Bag 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: V.C.I.
  • MB991827: MUT-III USB Cable
  • MB991910: MUT-III Main Harness A
• MB991865: Dummy resistor
• MB991884: 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 (MUT-III)  ."
   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 Scan Tool To Data Link Connector

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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 Use Troubleshooting/Inspection Service Points - HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).

   Fig 2: Connecting Scan Tool To Data Link Connector

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3. STEP 3. Using scan tool MB991958, read the diagnostic trouble code. 
   1. Turn the ignition switch to the "ON" position.
   2. Check if the DTC is set.
   3. Turn the ignition switch to the "LOCK" (OFF) position.

   Q: Is DTC B1519 set? 

   YES :  Go to Step 4.

   NO :  Go to  Step 5.

   Fig 3: Connecting Scan Tool To Data Link Connector

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4. STEP 4. Check the SRS-ECU connector C-124. 

   Q: Is connector correctly engaged? 

   YES :  Go to Step 5.

   NO :  Engage the connector correctly. Then go to  Step 9.

   Fig 4: Identifying Connector C-124 Terminals

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5. STEP 5. Check SRS-ECU connector C-124 and curtain air bag module (RH) connector D-08. (Using scan tool MB991958, read the diagnostic trouble code.) 
   1. Disconnect the negative battery terminal.
   2. Disconnect connectors C-124 and D-08, and then reconnect them. For connector D-08, use a flat-tipped screwdriver to unlock the locking button at the harness side connector by withdrawing it toward you in two stages, and then disconnect the connector.
   3. Connector the negative battery terminal.
   4. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

   Q: Is DTC B1440 set? 

   YES :  Go to Step 6.

   NO :  The procedure is complete. It is assumed that DTC B1440 set because connector C-124 or D-08 was engaged improperly.

   Fig 5: Disconnecting Connector C-123 Terminals

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   Fig 6: Identifying Connector D-08 Terminals

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   Fig 7: Removing Locking Button With Flat-Tipped Screwdriver

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6. STEP 6. Check the curtain air bag module (RH). (Using scan tool MB991958, read the diagnostic trouble code.) 
   1. Disconnect the negative battery terminal.
   2. Disconnect curtain air bag module (RH) connector D-08. Use a flat-tipped screwdriver to unlock the locking button at the harness side connector by withdrawing it toward you in two stages, and then disconnect the connector.
      Fig 8: Identifying Connector D-08 Terminals

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      Fig 9: Removing Locking Button With Flat-Tipped Screwdriver

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   3. Connect special tool MB991865 to special tool MB991884.
   4. Connect special tool MB991884 to the D-08 harness side connector.
   5. Connect the negative battery terminal.
   6. Erase diagnostic trouble code memory, and then check the diagnostic trouble code.

   Q: Is DTC B1440 set? 

   YES :  Go to Step 7.

   NO :  Replace the curtain air bag module (RH) (Refer to CURTAIN AIR BAG MODULE(S)  ). Then go to  Step 9.

   Fig 10: Connecting Special Tool MB991884 To D-08 Harness Side Connector

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7. STEP 7. Check the curtain air bag module (RH) circuit. Measure the resistance at the SRS-ECU connector C-124. 
   1. Disconnect SRS-ECU connector C-124.
      Fig 11: Identifying Connector C-124 Terminals

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      WARNING: To prevent the air bag from deploying unintentionally, disconnect the curtain air bag module connector D-08 to short the squib circuit.
   2. Disconnect curtain air bag module (RH) connector D-08. Use a flat-tipped screwdriver to unlock the locking button at the harness side connector by withdrawing it toward you in two stages, and then disconnect the connector.
      Fig 12: Identifying Connector D-08 Terminals

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      Fig 13: Removing Locking Button With Flat-Tipped Screwdriver

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      CAUTION: Insert an insulator such as a cable tie to a depth of 4 mm (0.16 inch) or more, otherwise the short spring will not be released.
   3. Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] between terminals 61, 62 and the short spring to release the short spring.
      Fig 14: Inserting Cable Tie Between Terminals 61, 62 And Short Spring

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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.
   4. Check for continuity between C-124 harness side connector terminals 61 and 62.

      It should be open circuit.

   Q: Does continuity exist? 

   YES :  Go to Step 8.

   NO :  Erase the diagnostic trouble code memory, and check diagnostic trouble code. If DTC B1440 set, replace the SRS-ECU (Refer to SRS CONTROL UNIT (SRS-ECU)  ). Then go to  Step 9.

   Fig 15: Checking Continuity Between C-124 Harness Side Connector Terminals 61 And 62

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8. STEP 8. Check the harness for short circuit between SRS-ECU connector C-124 (terminal No. 61 and 62) and curtain air bag module (RH) connector D-08 (terminal No. 1 and 2). 

   Q: Are harness wires between SRS-ECU connector C-124 (terminal No. 61 and 62) connector and curtain air bag module (RH) connector (terminal No. 1 and 2) in good condition? 

   YES :  Go to Step 9.

   NO :  Replace the harness wires between SRS-ECU connector C-124 and curtain air bag module (RH) connector D-08. Then go to Step 9.

   Fig 16: Identifying Connector C-124 Terminals

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   Fig 17: Identifying Connector D-08 Terminals

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9. STEP 9. 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 B1440 set? 

   YES :  Return to  Step 1.

   NO :  The procedure is complete.

   Fig 18: Connecting Scan Tool To Data Link Connector

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