Code No.B1470: Seat Belt Pre-Tensioner (LH) (Squib) System Fault 1 (Short Circuit between Terminals of the Squib Circuit)












caution If diagnosis code B1470 is set in the SRS-ECU, always diagnose the CAN main bus line.

OPERATION



DIAGNOSIS CODE SET CONDITIONS



PROBABLE CAUSES



  • Improper engaged connector or defective short spring*
  • Short circuit between the seat belt pre-tensioner (LH) (squib) circuit terminals
  • Damaged connector(s)
  • Malfunction of the SRS-ECU
note *: The squib circuit connectors integrate a "short" spring (which prevents the seat belt pre-tensioner from deploying unintentionally due to static electricity by shorting the positive wire to the earth wire in the squib circuit when the connectors are disconnected). Therefore, if connector D-25 or E-16 is damaged or improperly engaged, the short spring may not be released when the connector is connected.

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. M.U.T.-III diagnosis code
caution To prevent damage to M.U.T.-III MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting M.U.T.-III MB991958.
(1)Turn the ignition switch to the "ON" position.
(2)Check if the diagnosis code is set.
(3)Turn the ignition switch to the "LOOK" (OFF) position.

Q. Is diagnosis code B1519 set?
Go to Step 4.
Go to Step 5.

STEP 4. Connector check: SRS-ECU connector D-25.

Q. Is the connector correctly engaged?
Go to Step 5.
Engage code from memory the connector correctly. The procedure is complete.

STEP 5. Connector lock check: SRS-ECU connector D-25 and seat belt pre-tensioner (LH) connector E-16.
(1)Disconnect the negative battery terminal.

(2)Disconnect connectors D-25 and E-16, and then reconnect them. When disconnecting connector E-16, pull up the lock lever shown in the figure to the direction of the arrow, and release the lock. Then, disconnect connector E-16.
(3)Connect the negative battery terminal.
(4)Erase the diagnosis code from memory, and check the diagnosis code.

Q. Is diagnosis code B1470 set?

Go to Step 6.

The procedure is complete. It is assumed that diagnosis code B1470 set because connector D-25 or E-16 was engaged improperly.

STEP 6. Check the seat belt pre-tensioner.
(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 then check the diagnosis code.

Q. Is diagnosis code B1470 set?

Go to Step 7.

Replace the seat belt with pre-tensioner (LH) (Refer to ). Then go to Step 8.

STEP 7. Check the seat belt pre-tensioner (LH) circuit. Resistance 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)
caution Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.
Check for continuity between D-25 harness side connector terminals 7 and 8.
OK: Open circuit.

Q. Is the check result normal?

Go to Step 8.

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 8. Check whether the diagnosis code is reset.

Q. Is diagnosis code B1470 set?
Replace the SRS-ECU (Refer to ).
An intermittent malfunction is suspected (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).