B1452

DTC B1452: Curtain Air Bag Module (LH) (Squib) System Fault Ground Circuit (Short-Circuited to Ground) [ECLIPSE]













CAUTION:
If DTC B1452 is set in the SRS-ECU, always diagnose the CAN main bus line.

CIRCUIT OPERATION

- The SRS-ECU judges how severe a collision is by detecting signals from the left and right side impact sensors. If the impact is over a predetermined level, the SRS-ECU sends an ignition signal. At this time, if the side-airbag safing G-sensor is on, the SRS side-airbag will inflate.
- The ignition signal is input to the curtain air bag module (LH) to inflate the curtain air bag.

DTC SET CONDITIONS

This DTC is set if there is abnormal resistance between the input terminals of the curtain air bag module (LH) (squib).

TROUBLESHOOTING HITS

- Damaged wiring harnesses or connectors
- Short to the ground in the curtain air bag module (LH) (squib) harness
- Malfunction of the SRS-ECU

DIAGNOSIS

Required Special Tools:

- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
- MB991865: Dummy resistor
- MB991884: Resister harness

STEP 1. Using scan tool MB991958, diagnose the CAN bus line.





(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 Reading and Clearing Diagnostic Trouble Codes."
(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?

YES Go to Step 2.

NO Repair the CAN bus line CAN Bus Diagnostics Chart).

STEP 2. Recheck for diagnostic trouble code.





Check again if the DTC is set.
(1)Erase the DTC.
(2)Turn the ignition switch to "ON" position.
(3)Check if the DTC is set.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is DTC set?

YES Go to Step 3.

NO There is an intermittent malfunction such as poor engaged connector(s) or open circuit How to Cope With Intermittent Malfunctions).

STEP 3. Check the curtain air bag module (LH). (Using scan tool MB991958, read the diagnostic trouble code.)

(1)Disconnect the negative battery terminal.









(2)Disconnect curtain air bag module (LH) connector D-11. 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 MB991865 to special tool MB991884.
(4)Connect special tool MB991884 to the D-11 harness side connector.
(5)Connect the negative battery terminal.
(6)Erase diagnostic trouble code memory, and check the diagnostic trouble code.

Q. Is DTC B1452 set?

YES Go to Step 4.

NO Replace the curtain air bag module (LH) (Refer to Removal and Installation).
Then go to Step 6.

STEP 4. Check the curtain air bag module (LH) circuit. Measure the voltage at the SRS-ECU connector C-122.

(1)Disconnect the negative battery terminal.





(2)Disconnect SRS-ECU connector C-122.









(3)DANGER:
To prevent the air bag from deploying unintentionally, disconnect the curtain air bag module (LH) connector D-11 to short the squib circuit.

Disconnect curtain air bag module (LH) connector D-11. 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)
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 and the short spring to release the short spring.
(5)Connect the negative battery terminal.
(6)Turn the ignition switch to the "ON" position.





(7)
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 C-122 harness side connector terminals 5, 6 and body ground.
It should be open circuit.

Q. Does continuity exist?

YES Go to Step 5.

NO Erase the diagnostic trouble code memory, and check the diagnostic trouble code.
If DTC B1452 sets, replace the SRS-ECU (Refer to B1413). Then go to Step 6.

STEP 5. Check the harness wires for short circuit to ground between SRS-ECU connector C-122 (terminal No.5 and 6) and curtain air bag module (LH) connector D-11 (terminal No.2 and 1).









Q. Are the harness wires between SRS-ECU connector C-122 (terminal No.5 and 6). and curtain air bag module (LH) connector D-11 (terminal No.2 and 1) in good condition?

YES Go to Step 6.

NO Repair the harness wires between SRS-ECU connector C-122 and curtain air bag module (LH) connector D-11. Then go to Step 6.

STEP 6. Recheck for diagnostic trouble code.





Check again if the DTC is set.
(1)Erase the DTC.
(2)Turn the ignition switch to the "ON" position.
(3)Check if the DTC is set.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is DTC B1452 set?

YES Return to Step 1.

NO The procedure is complete.