B1C29

DTC B1C29: Side-air Bag Module (LH) (Squib) System (Squib Circuit Open)

Side-airbag Module (Squib) (LH) Circuit (Part 1):

Side-airbag Module (Squib) (LH) Circuit (Part 2):

CAUTION: If DTC B1C29 is set in the SRS-ECU, always diagnose the CAN bus lines.

CIRCUIT OPERATION
- The SRS-ECU judges how severe a collision is by detecting signals from the side impact sensor installed on the lower side of the center pillar. If the impact is over a predetermined level, the SRS-ECU sends an ignition signal. At this time, if the side collision safing G-sensor is on, the SRS air bag will inflate.
- The ignition signal is input to the side-air bag module to inflate the side-air bag.

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

TROUBLESHOOTING HINTS
- Open circuit in the side-air bag module (squib) (LH) circuit
- Improper connector contact
- Malfunction of the SRS-ECU

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
- MB991865: Dummy resistor
- MB991866: Resister harness

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







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.

1. Connect scan tool MB991958. Refer to "How to connect the scan tool." How To Connect The Scan Tool (M.U.T.-III)
2. Turn the ignition switch to "ON" position.
3. Diagnose the CAN bus line.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the check result satisfactory?

YES : Go to Step 2.

NO : Repair the CAN bus line.

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 the DTC set?

YES : Go to Step 3.

NO : There is an intermittent malfunction such as poor engaged connector(s) or open circuit.

STEP 3. Check the side-air bag module (LH).

1. Disconnect the negative battery terminal.







2. Unlock D-34 side-airbag module connector by sliding the locking button to the direction of the arrow as shown in the figure, and then disconnect the connector.







3. Connect special tool MB991865 to special tool MB991866.

CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.

4. Insert special tool MB991866 into the D-34 harness side connector by backprobing.
5. Connect the negative battery terminal.
6. Erase diagnostic trouble code memory, and then check the diagnostic trouble code.

Q: Is DTC B1C29 set?

YES : Go to Step 4.

NO : Replace the front seatback. Then go to Step 5.

STEP 4. Check the harness for open circuit between the SRS-ECU connector C-36 (terminal No.31 and 32) and the side-air bag module (LH) connector D-34 (terminal No.2 and 1).

1. Disconnect the negative battery terminal.







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-36 SRS-ECU connector.

DANGER: To prevent the air bag from deploying unintentionally, disconnect the side-air bag module (LH) connector D-34 to short the squib circuit.







3. Unlock D-34 side-airbag module connector by sliding the locking button to the direction of the arrow as shown in the figure, and then disconnect the connector.







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.

4. Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] between terminals 31, 32 and the short spring to release the short spring.







CAUTION: Do not insert a test probe into the terminal from D-34 harness side connector front side directly, as the connector contact pressure may be weakened.

5. Check for continuity between the following terminals. It should be less than 2 ohms.
- SRS-ECU connector C-36 (terminal No.31) and the side-air bag module (LH) connector D-34 (terminal No.2)
- SRS-ECU connector C-36 (terminal No.32) and the side-air bag module (LH) connector D-34 (terminal No.1)

Q: Does continuity exist?

YES : Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC B1C29 sets, replace the SRS-ECU. Then go to Step 5.

NO : Repair the harness wires between SRS-ECU connector C-36 and side-air bag module (LH) connector D-34. Then go to Step 5.

STEP 5.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 B1C29 set?

YES : Return to Step 1.

NO : The procedure is complete.