DTC B1B02: Driver’s Air Bag Module (1st squib) System (Squib Circuit Open)
DTC B1B06: Driver’s Air Bag Module (2nd squib) System (Squib Circuit Open)

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:
  


• Open circuit in the driver’s air bag module (squib) or harness
  


• Open circuit in the clock spring
  


• Malfunction of connector contact
  

TROUBLESHOOTING HINTS

• Open circuit in the clock spring
  
• Open circuit due to improper neutral position of the clock spring
  
• Open circuit in the driver’s air bag module (squib) circuit
  
• Disengaged driver’s air bag module (squib) connector
  
• Improper connector contact
  
• Malfunction of the SRS-ECU
  

(1) 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. 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)Slide the outer housing of the 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 test 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 terminal No.3 and 4 <2nd squib>) by backprobing. (5)Connect the negative battery terminal. (6) caution Always DTC B1B06 is set when checking DTC B1B02. 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 B1B06 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 4. Replace the driver’s air bag module (Refer to ) <Except RALLIART>, (Refer to ) <RALLIART>. Then go to Step 6.

(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 harness side of clock spring connector C-208 (terminal No.3 and 4 <1st squib> or terminal No.1 and 2 <2nd squib>) by backprobing. (5)Connect the negative battery terminal. (6) caution Always DTC B1B06 is set when checking DTC B1B02. 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 B1B06 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 clock spring (Refer to ) <Except RALLIART>, (Refer to ) <RALLIART>. Then go to Step 6.

(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)Disconnect the 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) 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. Check for continuity between the following terminals. It should be less than 2 ohms. SRS-ECU connector C-122 (terminal No.5) and the clock spring connector C-208 (terminal No.4) <1st squib> SRS-ECU connector C-122 (terminal No.6) and the clock spring connector C-208 (terminal No.3) <1st squib> SRS-ECU connector C-122 (terminal No.9) and the clock spring connector C-208 (terminal No.1) <2nd squib> SRS-ECU connector C-122 (terminal No.10) and the clock spring connector C-208 (terminal No.2) <2nd squib> Q. Does continuity exist? Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTCB1B02 <1st squib> or B1B06 <2nd squib> set, replace the SRS-ECU (Refer to ). Then go to Step 6. Repair the harness wires between SRS-ECU connector C-122 and clock spring connector C-208. Then go to Step 6.

	Return to Step 1.

	The procedure is complete.