Code No.B1420:
Side-airbag module (RH) (squib) system (short-circuit between terminals of the squib circuit)
OPERATION
In case of side collision, when the impact exceeding the threshold is applied to the vehicle,
and when the impact is simultaneously detected (turned ON) by the side impact sensor as well
as by the analog G-sensor in SRS-ECU, the electric current is supplied from SRS-ECU to the side-airbag
module (squib) of impacted side.
TROUBLE JUDGEMENT
The code is set when the short circuit occurs to between the terminals of SRS-ECU side-airbag module
(squib) circuit.
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.
(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 ).
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Go to Step 2
Go to Step 3)
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