CODE NO. B1C3A Driver’s pre-tensioner (squib) system (open circuit of squib circuit)
caution
If the diagnosis code B1C3A is set to SRS-ECU, be sure to diagnose the CAN bus line.
OPERATION
Only when the frontal impact exceeding 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 pre-tensioner (squib).
TROUBLE JUDGMENT
The code is set when the open circuit occurs to the SRS-ECU driver’s pre-tensioner (squib) circuit.
PROBABLE CAUSES
Poor contact of connector
Open circuit to driver’s pre-tensioner (squib) circuit
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. B1C3A 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-120 harness side connector.
(3)Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991884). (4)Connect the special tool resistor harness to the D-120 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. B1C3A set?
Go to Step 4.
Replace the seat belt with pre-tensioner (Refer to ).
STEP 4. Resistance measurement at the C-31 SRS-ECU connector and the D-120 pre-tensioner 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-120 harness side connector.
(4)Connect special tool resistor harness (MB991884) to the removed D-120 pre-tensioner connector. (5)Take the measurements below at the resistor harness and C-31 harness side connector.
Continuity between C-31 SRS-ECU connector terminal No. 45 and resistor harness connector terminal No. 2
Continuity between C-31 SRS-ECU connector terminal No. 46 and resistor harness connector terminal No. 1
OK: Continuity (less than 2 Ω)
Q.
Is the check result normal?
Go to Step 5.
Repair the wiring harness between the C-31 SRS-ECU connector terminal No. 45/46 and the D-120 pre-tensioner connector terminal No. 1/2.
STEP 5. Check whether the diagnosis code is reset.
Q.
Is the diagnosis code No. B1C3A 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 ).
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Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting 
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