Code No.B1451: Curtain air bag squib (LH) open-circuited












caution If diagnosis code B1451 is set in the SRS-ECU, always diagnose the CAN main bus line.

OPERATION



DIAGNOSIS CODE SET CONDITIONS



PROBABLE CAUSES



  • Improper connector contact
  • Open circuit in the curtain air bag module (LH) (squib) circuit
  • Malfunction of the SRS-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics.
Use the M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54D, Diagnosis ).

STEP 2. Check whether the diagnosis code is reset.
Check again if the diagnosis code is set.
(1)Erase the diagnosis code.
(2)Ignition: "LOCK" (OFF) position to "ON"
(3)On completion, check that the diagnosis code is not reset.

Q. Is the diagnosis code set?
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 ).

STEP 3. Check the curtain air bag module (LH).


(1)Disconnect the negative battery terminal.

(2)Disconnect curtain air bag module (LH) connector E-08. Use a flat-tipped screwdriver to unlock the locking button at the harness side connector by withdrawing it toward you in two stages, and then disconnect the connector.

(3)Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991884).
(4)Connect special tool MB991884 to the E-08 harness side connector.
(5)Connect the negative battery terminal.
(6)Erase the diagnosis code from memory, and then check the diagnosis code.

Q. Is diagnosis code B1451 set?

Go to Step 4.

Replace the curtain air bag module (LH) (Refer to ).

STEP 4. Resistance measurement between SRS-ECU connector D-25 (terminal No.5 and 6) and the curtain air bag module (LH) connector E-08 (terminal No.2 and 1).


(1)Disconnect the negative battery terminal.

(2)
danger To prevent the air bag from deploying unintentionally, disconnect the curtain air bag module (LH) connector E-08 to short the squib circuit.
Disconnect SRS-ECU connector D-25 and curtain air bag module (LH) connector E-08. For connector E-08, use a flat-tipped screwdriver to unlock the locking button at the harness side connector by withdrawing it toward you in two stages, and then disconnect the connector.

(3)
caution Insert an insulator such as a cable tie to a depth of 4 mm or more, otherwise the short spring will not be released.
Insert a cable tie [3 mm wide, 0.5 mm thick] between terminals 5, 6 and the short spring to release the short spring.

(4)Connect E-08 harness side connector to special tool resistor harness (MB991884).

(5)
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 the following terminals.

  • SRS-ECU connector D-25 (terminal No.5) and special tool terminal No.1
  • SRS-ECU connector D-25 (terminal No.6) and special tool terminal No.2
OK: Continuity (Less than 2 Ω)

Q. Are the check results normal?

Go to Step 5.

Repair the harness wire between SRS-ECU connector D-25 (terminal No.5 and 6) and curtain air bag module (LH) connector E-08 (terminal No.2 and 1).

STEP 5. Check whether the diagnosis code is reset.

Q. Is diagnosis code No.B1451 set?
Replace the SRS-ECU (Refer to ).
An intermittent malfunction is suspected (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).