DTC 22: Driver's Air Bag Module (Squib) System Fault 2 (Open in the Squib Circuit): Diagnosis

Required Special Tools: 

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)
  • MB991824: V.C.I.
  • MB991827: M.U.T.-III USB Cable
  • MB991911: M.U.T.-III Main Harness B
• MB991865: Dummy resister
• MB991866: Resister harness

1. STEP 1. Check the driver's air bag module (Using scan tool MB991958, read the diagnostic trouble code). 
   1. Disconnect the negative battery terminal.
   2. By sliding the A section (in the figure) of driver's air bag module connector C-201 in the arrow direction, disconnect the connector.
      Fig 1: Disconnecting Driver's Air Bag Module Connector C-201

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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 clock spring side air bag module connector C-201 by backprobing.
   5. Connect the negative battery terminal.
   6. Erase the diagnosis trouble code memory, and check the diagnosis trouble code.

   Q: Is DTC 22 set? 

   YES:  Go to Step 2.

   NO:  Replace the driver's air bag module (Refer to AIR BAG MODULE(S) AND CLOCK SPRING  ). Then go to  Step 4.

   Fig 2: Inserting Special Tool Into Clock Spring Side Air Bag Module Connector C-201

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2. STEP 2. Check the clock spring (Using scan tool MB991958, read the diagnostic trouble code). 
   1. Disconnect the negative battery terminal.
   2. Disconnect the clock spring connector C-205.
   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 clock spring harness side connector C-205 by backprobing.
   5. Connect the negative battery terminal.
   6. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

   Q: Is DTC 22 set? 

   YES:  Go to Step 3.

   NO:  Replace the clock spring (Refer to AIR BAG MODULE(S) AND CLOCK SPRING  ). Then go to  Step 4.

   Fig 3: Inserting Special Tool Into Clock Spring Side Air Bag Module Connector C-201

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3. STEP 3. Check the harness between the SRS-ECU connector C-12 (terminal No.11 and 12) and the clock spring connector C-205 (terminal No.3 and 4) for open circuit. 
   1. Disconnect SRS-ECU connector C-12 and clock spring connector C-205.
      CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.
      Fig 4: Identifying Connector C-12 Terminals

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      Fig 5: Disconnecting Clock Spring Connector C-205

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   2. Check for continuity between the following terminals. It should be less than 2 ohms.
      • SRS-ECU connector C-12 (terminal No.11) and the clock spring connector C-205 (terminal No.3)
      • SRS-ECU connector C-12 (terminal No.12) and the clock spring connector C-205 (terminal No.4)

   Q: Does continuity exist? 

   YES:  Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC 22 set, replace the SRS-ECU (Refer to SRS CONTROL UNIT (SRS-ECU)  ). Then go to Step 4.

   NO:  Repair the harness wires between SRS-ECU connector C-12 and clock spring connector C-205. Then go to Step 4.

   Fig 6: Checking Continuity Between SRS-ECU Connector C-12 And Clock Spring Connector C-205

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4. STEP 4. 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 22 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 ).

   Fig 7: Connecting Scan Tool To Data Link Connector

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