Code No.B1450 Left curtain air bag module (squib) system (short circuit between squib circuit terminals)

caution

If the diagnosis code B1450 is set to SRS-ECU, be sure to diagnose the CAN bus line.

OPERATION

In case of side collision, when the impact exceeding the threshold is applied to the vehicle, and when the impact is simultaneously detected (turned ON) by the side impact sensor as well as by the analogue G-sensor in SRS-ECU, the ignition signal is sent from SRS-ECU to the curtain air bag module (squib) of impacted side.

TROUBLE JUDGEMENT

The code is set when the short circuit occurs between the terminals of SRS-ECU curtain air bag module (squib) circuit.

PROBABLE CAUSES

Damaged short spring ^*
Short circuit between terminals of curtain air bag module (squib) circuit
Damaged connector(s)
Malfunction of SRS-ECU

note

*: The squib circuit connectors integrate a short spring (which prevents the air bags from being unintentionally deployed because of static electricity by shorting the positive wire to the earth wire in the squib circuit when the connectors are disconnected). Therefore, when the above codes are set, the short spring may not be released due to the damaged connector even when the connectors are connected.

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics.

Use 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 54C - Troubleshooting ).

STEP 2. Check whether the diagnosis code is reset.

(1)Connect the negative battery terminal.

(2)After erasing the diagnosis code memory, check the diagnosis code again.

(3)Disconnect the negative battery terminal.

Q. Is the diagnosis code No. B1450 set?

	Go to Step 3.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

STEP 3. Connector check: C-125 SRS-ECU, D-17 curtain air bag module connector.

(1)Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.

(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. After disconnecting the C-125 SRS-ECU connector, connect it again.

(3)After disconnecting the D-17 harness side connector, connect the connector again. For the D-17 connector disconnection, use the flat-tipped screwdriver to pull out the harness side connector locking button. After releasing the lock, disconnect the connector.
(4)Connect the negative battery terminal.
(5)After erasing the diagnosis code memory, check the diagnosis code again.
(6)Disconnect the negative battery terminal.

Q. Is the diagnosis code No. B1450 set?

Go to Step 4.

Replace the connector concerned.

STEP 4. Diagnosis check by dummy resistor connection.

(1)Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.

(2)Use the flat-tipped screwdriver to pull out the locking button of harness side connector. After releasing the lock, disconnect the D-17 curtain air bag module harness side connector.

(3)Connect the dummy resistor (Special tool: MB991865) to the resistor harness (Special tool: MB991884).
(4)Connect the resistor harness (special tool) to D-17 curtain air bag module connector.
(5)Connect the negative battery terminal.
(6)After erasing the diagnosis code memory, check the diagnosis code again.

Q. Is the diagnosis code No. B1450 set?

Go to Step 5.

Replace the left curtain air bag module (Refer to

STEP 5. Resistance measurement at the C-125 SRS-ECU connector.

(1)Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.

(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-125 SRS-ECU connector.

(3)

danger

To release C-23 SRS-ECU wiring harness side connector short spring in the following operations, disconnect D-17 air bag module connector in advance, and keep the squib circuit shorted.

Use the flat-tipped screwdriver to pull out the locking button of harness side connector. After releasing the lock, disconnect the D-17 harness side connector

(4)

caution

The short spring may not be released due to the insufficient insertion. Therefore, insert the insulator for 4 mm or more.

Insert an insulator (width: 3 mm, thickness: 0.5 mm) such as cable tie between the terminal 36/37 and the short spring, and release the short spring.
(5)Check the continuity between the C-125 wiring harness side connector terminal No. 36 and No. 37.
OK: No continuity

Q. Is the check result normal?

Go to Step 6.

Repair the wiring harness.

STEP 6. Check whether the diagnosis code is reset.

Q. Is the diagnosis code No. B1450 set?

	Replace SRS-ECU (Refer to ).

	Intermittent Malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).