CODE NO. B1C34 Driver’s lap pre-tensioner (squib) system (shorted to squib circuit power supply)












caution If the diagnosis code B1C34 is set to SRS-ECU, be sure to diagnose the CAN bus line.

OPERATION
Only when the frontal collision impact that exceeds the threshold is simultaneously detected (turned ON) by the front impact sensor as well as by the analogue G-sensor and safing G-sensor in SRS-ECU, the electric current is supplied from SRS-ECU to the lap pre-tensioner (squib).

TROUBLE JUDGMENT
The code is set when the SRS-ECU driver’s lap pre-tensioner (squib) circuit is shorted to power supply.

PROBABLE CAUSES

  • Poor contact of connector
  • Driver’s lap pre-tensioner (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. B1C34 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 D-26 harness side connector.

(3)Connect dummy resistor (MB991865) to special tool resistor harness (MB991884).
(4)Connect the special tool resistor harness to the D-26 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. B1C34 set?

Go to Step 4.

Replace the seat belt with pre-tensioner (Refer to ).

STEP 4. Voltage measurement at the C-31 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-31 SRS-ECU connector.

(3)Use the flat-tipped screwdriver to pull out the locking button of harness side connector. After releasing the lock, disconnect the D-26 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 No. 35 and 36, and then release the short spring.
(5)Connect the negative battery terminal.
(6)Ignition switch: ON
(7)Take the measurements below at the C-31 harness side connector.

  • Voltage between terminal No. 35/36 and body earth
OK: 0 V
(8)Disconnect the negative battery terminal.

Q. Is the check result normal?

Go to Step 5.

Repair the wiring harness between the C-31 SRS-ECU connector terminal No. 35/36 and the D-26 lap pre-tensioner connector terminal No. 2/1.

STEP 5. Check whether the diagnosis code is reset.

Q. Is the diagnosis code No. B1C34 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 ).