Code No.B1420: Side-airbag module (RH) (squib) system (short-circuit between terminals of the squib circuit)












OPERATION



TROUBLE JUDGEMENT



PROBABLE CAUSES



  • Improper engaged connector or defective short spring*
  • Short circuit between the side-airbag module (RH) (squib) circuit terminals
  • Damaged connector(s)
  • Malfunction of the SRS-ECU
note *: The squib circuit connectors integrate a short spring (which prevents the air bags from being unintentionally deployed because of static electricity by shorting the positive wire to the earth wire in the squib circuit when the connectors are disconnected). Therefore, when the above codes are set, the short spring may not be released due to the damaged connector even when the connectors are connected.

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code.

Q. Is diagnosis code B1519 set?
Go to Step 2
Go to Step 3

STEP 2. Connector lock check: B-111 SRS-ECU connector.
(1)Check that the negative auxiliary battery terminal is disconnected. If the negative auxiliary battery terminal is connected, disconnect it.
(2)After disconnecting the B-111 SRS-ECU connector, connect it again.
(3)Connect the negative auxiliary battery terminal.
(4)After erasing the diagnosis code memory, check the diagnosis code again.
(5)Disconnect the negative auxiliary battery terminal.

Q. Is diagnosis code B1420 set?
Go to Step 3
The procedure is complete. It is assumed that diagnosis code B1420 set as connector B-111 was engaged improperly.

STEP 3. Connector lock check: B-111 SRS-ECU connector and C-29 side-airbag module (RH) connector.
(1)Check that the negative auxiliary battery terminal is disconnected. If the negative auxiliary battery terminal is connected, disconnect it.

(2)Disconnect connectors B-111 and C-29, and then reconnect them. When disconnecting C-29 connector, unlock the connector by sliding the locking button to the direction of the arrow as shown in the figure, and then disconnect the connector.
(3)Connect the negative auxiliary battery terminal.
(4)After erasing the diagnosis code memory, check the diagnosis code again.
(5)Disconnect the negative auxiliary battery terminal.

Q. Is diagnosis code B1420 set?

Go to Step 4

The procedure is complete. It is assumed that diagnosis code B1420 set as connector B-111 or C-29 was engaged improperly.

STEP 4. Diagnosis check by dummy resistor connection.
(1)Check that the negative auxiliary battery terminal is disconnected. If the negative auxiliary battery terminal is connected, disconnect it.

(2)Disconnect the C-29 side-airbag module (RH) connector. When disconnecting C-29 connector, unlock the connector by sliding the locking button to the direction of the arrow as shown in the figure, and then disconnect the connector.

(3)Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991866).
(4)
caution Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.
Insert special tool (MB991866) into the harness side connector C-29 by backprobing.
(5)Connect the negative auxiliary battery terminal.
(6)After erasing the diagnosis code memory, check the diagnosis code again.

Q. Is diagnosis code B1420 set?

Go to Step 5

Replace the front seatback assembly (RH) (Refer to ).

STEP 5. Resistance measurement at the B-111 SRS-ECU connector.
(1)Check that the negative auxiliary battery terminal is disconnected. If the negative auxiliary battery terminal is connected, disconnect it.
(2)Disconnect the B-111 SRS-ECU connector.

(3)
danger To release the connector short spring in the following operations, disconnect this side-airbag module connector, and keep the squib circuit shorted.
Disconnect C-29 side-airbag module (RH) connector. When disconnecting C-29 connector, unlock the connector by sliding the locking button to the direction of the arrow as shown in the figure, and then disconnect the connector.

(4)
caution The short spring may not be released due to the insufficient insertion, thus insert for 4 mm or more.
Insert the insulator (width: 3 mm, thickness: 0.5 mm) such as cable tie between the terminals Nos. 53 and 54, and then 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.
Take the measurements below at the B-111 harness side connector.

  • Continuity between terminals 53 and 54
OK: No continuity

Q. Is the check result normal?

Go to Step 6

Repair the harness wires between B-111 SRS-ECU connector (terminal No.53 and 54) and C-29 side-airbag module (RH) connector (terminal No.1 and 2).

STEP 6. Check whether the diagnosis code is reset.

Q. Is diagnosis code B1420 set?
Replace the SRS-ECU (Refer to ).
An intermittent malfunction is suspected (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).