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)

CIRCUIT OPERATION

• The SRS-ECU judges how severe a collision is by detecting signals from the front impact sensors and the front air bag analog G-sensor. If the impact is over a predetermined level, the SRS-ECU sends an ignition signal. At this time, if the front air bag safing G-sensor is on, the SRS air bag will inflate.
  
• The ignition signal is input to the air bag module via the clock spring to inflate the air bag.
  

DTC SET CONDITIONS

• This DTC is set if there is abnormal resistance between the input terminals of the driver’s air bag module (squib). The most likely causes for this code to be set are the followings:
  


• Short circuit in driver’s air bag module (squib) or harness
  
• Short circuit in the clock spring
  

• Improper engaged connector or defective short spring*
  
• Short circuit in the clock spring
  
• Short circuit between the driver’s air bag module (squib) circuit terminals
  
• Damaged connector(s)
  
• Malfunction of the SRS-ECU
  

note

*: The squib circuit connectors integrate a "short" spring (which prevents the air bag from deploying unintentionally due to static electricity by shorting the positive wire to the ground wire in the squib circuit when the connectors are disconnected) (Refer to ). Therefore, if connector C-122, C-207 or C-208 is damaged or improperly engaged, the short spring may not be released when the connector is connected.

(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? Go to Step 2. Repair the CAN bus line (Refer to GROUP 54C, Diagnosis ).

	Go to Step 3.

	There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).

(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.

(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? Go to Step 4. 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.

(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.

(3)Connect special tool MB991865 to special tool MB991866. (4) caution Do not insert a probe into the terminal from its front side directly as the connector contact pressure may be weakened. 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. (6) 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. Erase the diagnostic trouble code memory, and check the diagnostic trouble code. Q. Is the checked DTC set? Go to Step 5. Replace the driver’s air bag module (Refer to ) <Except RALLIART>, (Refer to ) <RALLIART>. Then go to Step 8.

(3)Connect special tool MB991865 to special tool MB991866. (4) 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. 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. (6) 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. Erase the diagnostic trouble code memory, and check the diagnostic trouble code. Q. Is the checked DTC set? Go to Step 6. Replace the clock spring (Refer to ) <Except RALLIART>, (Refer to ) <RALLIART>. Then go to Step 8.

(2)While pushing the part "A" indicated in the figure 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. (3) danger To prevent the air bag from deploying unintentionally, disconnect clock spring connector C-208 to short the squib circuit. Disconnect clock spring connector C-208.

(4) 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. 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.

(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? 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 ). Then go to Step 8. Go to Step 7.

	Go to Step 8.

	Repair the harness wires between SRS-ECU connector C-122 and clock spring connector C-208. Then go to Step 8.

	Return to Step 1.

	The procedure is complete.