Code No.B1451: Curtain air bag module (squib) (RH) system (open-circuited in the squib circuit)




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

OPERATION


The SRS-ECU judges how severe a collision is by detecting signals from the side impact sensors and the side-airbag safing G-sensor. If the impact is over a predetermined level, the SRS-ECU outputs an ignition signal. At this time, if the side-airbag safing G-sensor is on, the curtain air bag module will deploy.

DIAGNOSIS CODE SET CONDITIONS


This diagnosis code is set if curtain air bag module squib (LH) wire(s) are open-circuited.

PROBABLE CAUSES



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 54F, 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) (M.U.T.-III diagnosis code).


(1)Disconnect the negative battery terminal.

(2)Disconnect the intermediate connector G-22 (connection between rear floor harness and floor harness).

(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 resistor harness probe into intermediate connector G-22 (floor harness side) by backprobing.
(5)Connect the negative battery terminal.
(6)Erase diagnosis code memory, and then check the diagnosis code.

Q. Is diagnosis code B1451 set?

Go to Step 4 .

Go to Step 5 .

STEP 4. Resistance measurement between SRS-ECU connector C-120 (terminal No.5 and 6) and the intermediate connector G-22 (terminal No.1 and 2).


(1)Disconnect the negative battery terminal.

(2)Disconnect SRS-ECU connector C-120.

(3)Disconnect the intermediate connector G-22 (connection between rear floor harness and floor harness).

(4)
caution Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.
Resistance measurement between the following terminals.

  • SRS-ECU connector C-120 terminal No.5 and intermediate connector G-22 (floor harness side) terminal No.1
  • SRS-ECU connector C-120 terminal No.6 and intermediate connector G-22 (floor harness side) terminal No.2
OK: Less than 2 Ω

Q. Are the check results normal?

Go to Step 6 .

Repair the harness wire between SRS-ECU connector C-120 (terminal No.5 and 6) and intermediate connector G-22 (terminal No.1 and 2).

STEP 5. Resistance measurement between intermediate connector G-22 (terminal No.1 and 2) and the curtain air bag module (LH) connector G-01 (terminal No.1 and 2).
(1)Disconnect the negative battery terminal.

(2)Disconnect the intermediate connector G-22 (connection between rear floor harness and floor harness connector).


(3)Disconnect curtain air bag module (LH) connector G-01, and measure at the wiring harness side. For connector G-01, 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.

(4)Connect G-01 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.
Resistance measurement between the following terminals.

  • Intermediate connector (rear floor harness side) G-22 terminal No.2 and special tool terminal No.2
  • Intermediate connector (rear floor harness side) G-22 terminal No.1 and special tool terminal No.1
OK: Less than 2 Ω

Q. Is the check result normal?

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

Repair the harness wire between intermediate connector G-22 (terminal No.1 and 2) and curtain air bag module (LH) connector G-01 (terminal No.1 and 2).

STEP 6. 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 Use Troubleshooting/Inspection Service Points ).