Toyota 4Runner: Short in Driver Side Squib Circuit (B1800/51-B1803/51)

Toyota 4Runner Service Manual / Vehicle Interior / Supplemental Restraint Systems / Airbag System / Short in Driver Side Squib Circuit (B1800/51-B1803/51)

DESCRIPTION

The driver side squib circuit consists of the center airbag sensor, spiral cable and steering pad.
The circuit instructs the SRS to deploy when deployment conditions are met.
These DTCs are stored when a malfunction is detected in the driver side squib circuit.

DTC Code	DTC Detection Condition	Trouble Area
B1800/51	One of the following conditions is met: The center airbag sensor detects a line short circuit signal 5 times in the driver side squib circuit during the primary check. A driver side squib malfunction. A spiral cable malfunction. A center airbag sensor malfunction.	Instrument panel wire Spiral cable sub-assembly Steering pad (Driver side squib) Center airbag sensor assembly
B1801/51	One of the following conditions is met: The center airbag sensor detects an open circuit signal in the driver side squib circuit for 2 seconds. A driver side squib malfunction. A spiral cable malfunction. A center airbag sensor malfunction.	Instrument panel wire Spiral cable sub-assembly Steering pad (Driver side squib) Center airbag sensor assembly
B1802/51	One of the following conditions is met: The center airbag sensor detects a short circuit to ground signal in the driver side squib circuit for 0.5 seconds. A driver side squib malfunction. A spiral cable malfunction. A center airbag sensor malfunction.	Instrument panel wire Spiral cable sub-assembly Steering pad (Driver side squib) Center airbag sensor assembly
B1803/51	One of the following conditions is met: The center airbag sensor detects a short circuit to B+ signal in the driver side squib circuit for 0.5 seconds. A driver side squib malfunction. A spiral cable malfunction. A center airbag sensor malfunction.	Instrument panel wire Spiral cable sub-assembly Steering pad (Driver side squib) Center airbag sensor assembly

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When installing the spiral cable and steering wheel, be sure to adjust the spiral cable as it may break if the steering wheel is turned before adjusting the spiral cable (See page ).
When disconnecting the cable from the negative (-) battery terminal while performing repairs, some systems need to be initialized after the cable is reconnected (See page ).

HINT:

To perform the simulation method, enter check mode (signal check) with the Techstream (See page ), and then wiggle each connector of
the airbag system or drive the vehicle on various types of road (See page ).

PROCEDURE

1.	CHECK STEERING PAD (DRIVER SIDE SQUIB)

(a) Turn the ignition switch off.

(b) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.

(d) Connect the white wire side of SST (resistance: 2.1 Ω) to connector E (orange connector).

CAUTION:

Never connect the tester to the steering pad (driver side squib) for measurement, as this may lead to a serious injury due to airbag deployment.

NOTICE:

Do not forcibly insert SST into the terminals of the connector when connecting SST.
Insert SST straight into the terminals of the connector.

SST: 09843-18061

(e) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

(f) Turn the ignition switch to ON, and wait for at least 60 seconds.

(g) Clear the DTCs (See page ).

(h) Turn the ignition switch off.

(i) Turn the ignition switch to ON, and wait for at least 60 seconds.

(j) Check for DTCs (See page ).

OK:

DTC B1800, B1801, B1802 or B1803 is not output.

HINT:

Codes other than DTC B1800, B1801, B1802 and B1803 may be output at this time, but they are not related to this check.

Text in Illustration

*1	Driver Side Squib
*2	Spiral Cable
*3	Center Airbag Sensor
*4	Connector E
*5	SST
*a	Front view of wire harness connector (to Driver Side Squib)
*b	Color: Orange

REPLACE STEERING PAD

2.	CHECK CONNECTOR

(a) Turn the ignition switch off.

(b) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.

(d) Check that the spiral cable connectors (on the steering pad side) are not damaged.

OK:

The lock button is not disengaged, and the claw of the lock is not deformed or damaged.

Text in Illustration

*1	Driver Side Squib
*2	Spiral Cable
*3	Center Airbag Sensor

REPLACE SPIRAL CABLE SUB-ASSEMBLY

3.	CHECK DRIVER SIDE SQUIB CIRCUIT

(a) Disconnect the connectors from the center airbag sensor.

(b) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
Z12-2 (D+) - Body ground	Ignition switch ON	Below 1 V
Z12-1 (D-) - Body ground	Ignition switch ON	Below 1 V

(d) Turn the ignition switch off.

(e) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.

(f) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
Z12-2 (D+) - Z12-1 (D-)	Always	Below 1 Ω

(g) Release the activation prevention mechanism built into connector B (See page ).

(h) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
Z12-2 (D+) - Z12-1 (D-)	Always	1 MΩ or higher
Z12-2 (D+) - Body ground	Always	1 MΩ or higher
Z12-1 (D-) - Body ground	Always	1 MΩ or higher

Text in Illustration

*1	Driver Side Squib
*2	Spiral Cable
*3	Center Airbag Sensor
*4	Connector E
*a	Front view of wire harness connector (to Driver Side Squib)
*b	Color: Orange

GO TO STEP 5

4.	CHECK CENTER AIRBAG SENSOR

(a) Connect the connectors to the steering pad and center airbag sensor.

(b) Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.

(d) Clear the DTCs (See page ).

(e) Turn the ignition switch off.

(f) Turn the ignition switch to ON, and wait for at least 60 seconds.

(g) Check for DTCs (See page ).

OK:

DTC B1800, B1801, B1802 or B1803 is not output.

HINT:

Codes other than DTC B1800, B1801, B1802 and B1803 may be output at this time, but they are not related to this check.

Text in Illustration

*1	Driver Side Squib
*2	Spiral Cable
*3	Center Airbag Sensor

USE SIMULATION METHOD TO CHECK

REPLACE CENTER AIRBAG SENSOR ASSEMBLY

5.	CHECK INSTRUMENT PANEL WIRE (CENTER AIRBAG SENSOR - SPIRAL CABLE)

(a) Restore the released activation prevention mechanism of connector B to its original condition.

(b) Disconnect the instrument panel wire connector from the spiral cable.

(d) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
F24-1 (D+) - Body ground	Ignition switch ON	Below 1 V
F24-2 (D-) - Body ground	Ignition switch ON	Below 1 V

(e) Turn the ignition switch off.

(f) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.

(g) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
F24-1 (D+) - F24-2 (D-)	Always	Below 1 Ω

(h) Release the activation prevention mechanism built into connector B (See page ).

(i) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
F24-1 (D+) - F24-2 (D-)	Always	1 MΩ or higher
F24-1 (D+) - Body ground	Always	1 MΩ or higher
F24-2 (D-) - Body ground	Always	1 MΩ or higher

Text in Illustration

*1	Instrument Panel Wire
*2	Spiral Cable
*3	Center Airbag Sensor
*4	Connector C
*a	Rear view of wire harness connector (to Spiral Cable)

REPLACE SPIRAL CABLE SUB-ASSEMBLY

REPLACE INSTRUMENT PANEL WIRE

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