Code No.B1473: Seat Belt Pre-tensioner Squib (LH) (Power Supply Side) Short-circuited












caution If diagnosis code B1473 is set in the SRS-ECU, always diagnose the CAN main bus line.

OPERATION



DIAGNOSIS CODE SET CONDITIONS



PROBABLE CAUSES



  • Damaged wiring harnesses or connectors
  • Short to the power supply in the seat belt pre-tensioner (LH) (squib) harness
  • Malfunction of the SRS-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics.
Use the 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 54D, Diagnosis ).

STEP 2. Check whether the diagnosis code is reset.
Check again if the diagnosis code is set.
(1)Erase the diagnosis code.
(2)Ignition: "LOCK" (OFF) position to "ON"
(3)On completion, check that the diagnosis code is not reset.

Q. Is the diagnosis code set?
Go to Step 3.
There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).

STEP 3. Check the seat belt pre-tensioner (LH).
(1)Disconnect the negative battery terminal.

(2)Pull up the lock lever shown in the figure to the direction of the arrow, and release the lock. Then, disconnect seat belt pre-tensioner (LH) connector E-16.

(3)Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991866).
(4)Connect special tool MB991866 to the E-16 harness side connector.
(5)Connect the negative battery terminal.
(6)Erase the diagnosis code from memory, and check the diagnosis code.

Q. Is diagnosis code B1473 set?

Go to Step 4.

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

STEP 4. Check the seat belt pre-tensioner circuit. (LH) Voltage measurement at the SRS-ECU connector D-25.
(1)Disconnect the negative battery terminal.
(2)Disconnect SRS-ECU connector D-25.

(3)
danger To prevent the seat belt pre-tensioner from deploying unintentionally, disconnect the seat belt pre-tensioner (LH) connector E-16 to short the squib circuit.
Pull up the lock lever shown in the figure to the direction of the arrow, and release the lock. Then, disconnect seat belt pre-tensioner (LH) connector E-16.

(4)
caution Insert an insulator such as a cable tie to a depth of 4mm or more, otherwise the short spring will not be released.
Insert a cable tie [3 mm wide, 0.5 mm thick] between terminals 7, 8 and the short spring to release the short spring.
(5)Connect the negative battery terminal.
(6)Turn the ignition switch to the "ON" position.
(7)
caution Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.
Measure the voltage between D-25 harness side connector terminals 7, 8 and body earth.
OK: 0 V

Q. Is the check result normal?

Go to Step 5.

Repair the harness wires between SRS-ECU connector D-25 (terminal No.7 and 8) and seat belt pre-tensioner (LH) connector E-16 (terminal No.1 and 2).

STEP 5. Check whether the diagnosis code is reset.

Q. Is diagnosis code B1473 set?
Replace the SRS-ECU (Refer to ).
An intermittent malfunction is suspected (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).