Code No.B1400: Driver’s Air Bag Module (1st Squib) System Fault 1 (Short Circuit between Terminals of the Squib Circuit)
Code No.B1480: Driver’s Air Bag Module (2nd Squib) System Fault 1 (Short Circuit between Terminals of the Squib Circuit)

OPERATION

• The SRS-ECU judges how severe a collision is by detecting signals from the front impact sensors and the front air bag analogue 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.
  

DIAGNOSIS CODE SET CONDITIONS

• This diagnosis code is set if there is abnormal resistance between the input terminals of the driver’s side 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
  

PROBABLE CAUSES

• 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 earth wire in the squib circuit when the connectors are disconnected). (Refer to ). Therefore, if connector C-119, C-309 or C-303 is damaged or improperly engaged, the short spring may not be released when the connector is connected.

	Go to Step 2 .

	Repair the CAN bus line (Refer to GROUP 54F, 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 ).

	Go to Step 4 .

	Go to Step 5 .

Q. Is the connector correctly engaged? Go to Step 5 . Engage the connector correctly. Then go to Step 10 .

(2)Disconnect connectors C-119, C-309 and C-303, and then reconnect them. (3)Connect the negative battery terminal. (4)Erase the diagnosis code memory, and check the diagnosis code. Q. Is diagnosis code B1400 <1st squib> or B1480 <2nd squib> set? Go to Step 6 . The procedure is complete. It is assumed that diagnosis code B1400 <1st squib> or B1480 <2nd squib> set because connector C-119, C-309 or C-303 was engaged improperly.

(2)Slide the outer housing of the clock spring side of driver’s air bag module connector C-303 in the arrow direction shown, and disconnect the connector.

(3)Connect special tool dummy resistor (MB991865) to special tool resistor harness (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-303 (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 diagnosis code B1481 is set when checking diagnosis code B1400. This is because the second side terminal is isolated when checking it, diagnosis code B1481 is set but this is not a fault. In addition, always diagnosis code B1401 is set when checking diagnosis code B1480 because the first side terminal is isolated. Erase the diagnosis code memory, and check the diagnosis code. Q. Is the checked diagnosis code set? Go to Step 7 . Replace the driver’s air bag module (Refer to ). Then go to Step 10 .

(2)Disconnect the clock spring connector C-309.

(3)Connect special tool dummy resistor (MB991865) to special tool resistor harness (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 harness side connector C-309 (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 diagnosis code B1481 is set when checking diagnosis code B1400. This is because the second side terminal is isolated when checking it, diagnosis code B1481 is set but this is not a fault. In addition, always diagnosis code B1401 is set when checking diagnosis code B1480 because the first side terminal is isolated. Erase the diagnosis code memory, and check the diagnosis code. Q. Is the checked diagnosis code set? Go to Step 8 . Replace the clock spring (Refer to ). Then go to Step 10 .

(1)Disconnect SRS-ECU connector C-119.

(2) danger To prevent the air bag from deploying unintentionally, disconnect clock spring connector C-309 to short the squib circuit. Disconnect clock spring connector C-309.

(3) caution Insert an insulator such as a cable tie to a depth of 4mm or more, otherwise the short spring will not be released. Insert a cable tie [3 mm wide, 0.5 mm thick] between terminals 36, 37 <1st squib> or 33, 34 <2nd squib> and the short spring to release the short spring.

(4) caution Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened. Check for continuity between C-119 harness side connector terminals 36 and 37 <1st squib> or 33 and 34 <2nd squib>. OK: Open circuit Q. Is the check result normal? Erase the diagnosis code memory, and check the diagnosis code. If diagnosis code B1400 <1st squib> or B1481 <2nd squib> set, replace the SRS-ECU (Refer to ). Then go to Step 10 . Go to Step 9 .

Q. Are harness wires between SRS-ECU connector C-119 (terminal No.36 and 37 <1st squib> or No.33 and 34 <2nd squib>) and clock spring connector C-309 (terminal No.3 and 4 <1st squib> or No.1 and 2 <2nd squib>) in good condition? Go to Step 10 . Replace the harness wires between SRS-ECU connector C-119 and clock spring connector C-309. Then go to Step 10 .

	Return to Step 1 .

	The procedure is complete.