DTC B1410: Passenger's (Front) Air Bag Module (1st Squib) System Fault 1 (Short Circuit between Terminals of the Squib Circuit); DTC B1490: Passenger's (Front) Air Bag Module (2nd Squib) System Fault 1 (Short Circuit between Terminals of the Squib Circuit): 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 resister
• 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 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 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 ).

   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. 
   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. Turn the ignition switch to the "ON" position.
   2. Check if the DTC is set.
   3. Turn the ignition switch to the "LOOK (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 SRS-ECU connector C-26. 

   Q: Is the connector correctly engaged? 

   YES  : Go to Step 5.

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

   Fig 4: Identifying Connector C-26 Terminals

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5. STEP 5. Check SRS-ECU connector C-26 and passenger's air bag module connector C-09. (Using scan tool MB991958, read the diagnostic trouble code.) 
   1. Disconnect the negative battery terminal.
   2. Disconnect connectors C-26 and C-09, and then reconnect them.
      Fig 5: Identifying Connector C-26 Terminals

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      Fig 6: Identifying Connector C-09 Terminals

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   3. Slide the outer housing of the clock spring side of driver's air bag module connector C-09 in the arrow direction shown, and disconnect the connector.
   4. Connect the negative battery terminal.
   5. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

   Q: Is DTC B1410 < 1st squib > or B1490 < 2nd squib > set? 

   YES  : Go to Step 6.

   NO  : The procedure is complete. It is assumed that DTC B1410 < 1st squib > or B1490 < 2nd squib > set as connector C-26 or C-09 was engaged improperly.

   Fig 7: Identifying Connector C-09

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6. STEP 6. Check the passenger's air bag module. (Using scan tool MB991958, read the diagnostic trouble code.) 
   1. Disconnect the negative battery terminal.
   2. Disconnect the passenger's air bag module connector C-09.
      Fig 8: Identifying Connector C-09 Terminals

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   3. Slide the outer housing of the clock spring side of passenger's air bag module connector C-09 in the arrow direction shown, and disconnect the connector.
      Fig 9: Identifying Connector C-09

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   4. 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.
   5. Insert special tool MB991866 into the harness side connector C-09 (terminal No. 1 and 2 < 1st squib > or terminal No. 3 and 4 < 2nd squib >) by backprobing.
   6. Connect the negative battery terminal.
      Fig 10: Inserting Special Tool MB991866 Into Harness Side Connector C-09

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      CAUTION: Always DTC B1491 is set when checking DTC B1410. This is because the second side terminal is isolated when checking it, DTC B1491 is set but this is not a fault. In addition, always DTC B1411 is set when checking DTC B1490 because the first side terminal is isolated.
   7. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

   Q: Is the checked DTC set? 

   YES  : Go to Step 7.

   NO  : Replace the passenger's air bag module (Refer to AIR BAG MODULES AND CLOCK SPRING  ). Then go to  Step 9.

7. STEP 7. Check the passenger's air bag module circuit at SRS-ECU connector C-26. 
   1. Disconnect SRS-ECU connector C-26.
      Fig 11: Identifying Connector C-26 Terminals

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      WARNING: To prevent the air bag from deploying unintentionally, disconnect the passenger's air bag module connector C-09 to short the squib circuit.
   2. Disconnect the passenger's air bag module connector C-09.
      Fig 12: Identifying Connector C-09 Terminals

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   3. Slide the outer housing of the clock spring side of driver's air bag module connector C-09 in the arrow direction shown, and disconnect the connector.
      Fig 13: Identifying Connector C-09

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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.
   4. Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] between terminals 27 and 28 < 1st squib > or 30 and 31 < 2nd squib >, and the short spring to release the short spring.
      Fig 14: Inserting Cable Tie Between Terminals 27, 28 (1st Squib) And Short Spring

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      Fig 15: Inserting Cable Tie Between Terminals 30, 31 (2nd Squib) 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.
   5. Check for continuity between C-26 harness side connector terminals 27 and 28 < 1st squib > or 30 and 31 < 2nd squib >.

      It should be open circuit.

      Fig 16: Checking Continuity Between C-26 Harness Side Connector Terminals 27 And 28 (1st Squib)

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   Q: Does continuity exist? 

   YES  : Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC B1410 < 1st squib > or B1490 < 2nd squib > set, replace the SRS-ECU. (Refer to SRS CONTROL UNIT (SRS-ECU)  ). Then go to  Step 9.

   NO  : Go to Step 8.

   Fig 17: Checking Continuity Between C-26 Harness Side Connector Terminals 30 And 31 (2nd Squib)

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8. STEP 8. Check the harness for short circuit between SRS-ECU connector C-26 (terminal No. 27 and 28 < 1st squib > or terminal No. 30 and 31 < 2nd squib >) and passenger's air bag module connector C-09 (terminal No. 1 and 2 < 1st squib > terminal No. 4 and 3 < 2nd squib >). 

   Q: Are harness wires between SRS-ECU connector C-26 (terminal No. 27 and 28 < 1st squib > or terminal No. 30 and 31 < 2nd squib >) and passenger's air bag module connector C-09 (terminal No. 1 and 2 < 1st squib > terminal No. 4 and 3 < 2nd squib >) in good condition? 

   YES  : Go to Step 9.

   NO  : Replace the harness wires between SRS-ECU connector C-26 and passenger's air bag module connector C-09. Then go to Step 9.

   Fig 18: Identifying Connector C-26 Terminals

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   Fig 19: Identifying Connector C-09 Terminals

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9. STEP 9. Check 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 B1410 < 1st squib > or B1490 < 2nd squib > set? 

   YES  : Return to  Step 1.

   NO  : The procedure is complete.

   Fig 20: Connecting Scan Tool To Data Link Connector

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