Code No.B1413 Passenger’s (front) air bag module (squib) system (shorted to squib circuit power supply)


caution
  • If the diagnosis code B1413 is set to SRS-ECU, be sure to diagnose the CAN bus line.
  • Follow the diagnosis procedure below. If diagnosis code B1413 is set, check squib side circuit

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 in SRS-ECU, the electric current is supplied from SRS-ECU to the passenger’s (front) air bag module (squib).

TROUBLE JUDGEMENT


The code is set when the input terminal of SRS-ECU passenger’s (front) air bag module (squib) shorted to power supply.

PROBABLE CAUSES



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. B1413 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 wiring harness side connector, and release the lock.

(3)Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991866).
(4)
caution Do not insert a probe directly into the terminal from the connector front side as the connector contact pressure may be weakened.
Insert the resistor harness probe from the back of harness side connector ASQ+, ASQ- line.
(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. B1413 set?

Go to Step 4.

Replace the passenger’s (front) 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 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 wiring harness side connector, and release the lock.

(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 ASQ+, ASQ- line, and then 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.

  • Continuity between ASQ+, ASQ- 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 ASQ+, ASQ- line between the SRS-ECU connector and the passenger’s (front) air bag module connector.

STEP 5. Check whether the diagnosis code is reset.

Q. Is the diagnosis code No. B1413 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 ).