Code No.B1634 Driver’s knee air bag module (squib) system (shorted to squib circuit power supply)

caution

If the diagnosis code B1634 is set to SRS-ECU, be sure to diagnose the CAN bus line.

OPERATION

TROUBLE JUDGEMENT

PROBABLE CAUSES

Poor contact of connector
Driver’s knee air bag module (squib) harness shorted to power supply
Malfunction of SRS-ECU

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. B1634 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. 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 knee air bag module harness side connector.

(3)Connect dummy resistor (MB991865) to special tool resistor harness (MB991884).
(4)Connect the special tool resistor harness to the knee air bag module harness side connector.
(5)Connect the negative battery terminal.
(6)After erasing the diagnosis code memory, check the diagnosis code again.
(7)Disconnect the negative battery terminal.

Q. Is the diagnosis code No. B1634 set?

Go to Step 4.

Replace the driver’s knee air bag module (Refer to

STEP 4. Voltage measurement at the 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 SRS-ECU connector.

(3)

danger

To release the SRS-ECU connector short spring in the following operations, disconnect this harness side connector, 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 knee air bag module 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 KDS-, KDS+ line and the short spring, and release the short spring.
(5)Connect the negative battery terminal.
(6)Ignition switch: ON
(7)Take the measurements below at the SRS-ECU harness side connector.

Voltage between KDS-, KDS+ line and body earth

OK: 1 V or less
(8)Disconnect the negative battery terminal.

Q. Is the check result normal?

Go to Step 5.

Repair the wiring harness KDS-, KDS+ line between the SRS-ECU connector and the knee air bag module connector.

STEP 5. Check whether the diagnosis code is reset.

Q. Is the diagnosis code No. B1634 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 ).