Toyota 4Runner: Lost Communication with Front Airbag Sensor LH (B1617/84,B1618/84)

Toyota 4Runner Service Manual / Vehicle Interior / Supplemental Restraint Systems / Airbag System / Lost Communication with Front Airbag Sensor LH (B1617/84,B1618/84)

DESCRIPTION

The front airbag sensor LH circuit consists of the center airbag sensor and front airbag sensor LH.

The front airbag sensor LH detects impacts to the vehicle and sends signals to the center airbag sensor to determine if the airbag should be deployed.

DTC B1617/84 or B1618/84 is stored when a malfunction is detected in the front airbag sensor LH circuit.

DTC Code	DTC Detection Condition	Trouble Area
B1617/84	One of the following conditions is met: The center airbag sensor detects a line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to B+ signal in the front airbag sensor LH circuit for 2 seconds. A front airbag sensor LH malfunction. A center airbag sensor malfunction.	Instrument panel wire Engine room main wire Front airbag sensor LH Center airbag sensor assembly
B1618/84	One of the following conditions is met: The center airbag sensor detects a line short circuit signal, open circuit signal, short circuit to ground signal or short circuit to B+ signal in the front airbag sensor LH circuit for 2 seconds. A front airbag sensor LH malfunction. A center airbag sensor malfunction.	Instrument panel wire Engine room main wire Front airbag sensor LH Center airbag sensor assembly

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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 ).

PROCEDURE

1.	CHECK CONNECTION OF CONNECTORS

(a) Turn the ignition switch off.

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

OK:

The connectors are properly connected.

CONNECT CONNECTORS PROPERLY

2.	CHECK CONNECTORS

(a) Disconnect the connectors from the center airbag sensor and front airbag sensor LH.

(b) Check that the connectors (on the center airbag sensor side and front airbag sensor LH side) are not damaged.

OK:

The connectors are not deformed or damaged.

Text in Illustration

*1	Front Airbag Sensor LH
*2	Center Airbag Sensor

REPLACE HARNESS AND CONNECTOR

3.	CHECK FRONT AIRBAG SENSOR LH CIRCUIT

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

Text in Illustration

*1	Front Airbag Sensor LH	*2	Center Airbag Sensor
*3	Connector E	*4	Connector B
*5	Service Wire	-	-
*a	Front view of wire harness connector (to Front Airbag Sensor LH)	*b	Rear view of wire harness connector (to Center Airbag Sensor)

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
A13-2 (+SL) - Body ground	Ignition switch ON	Below 1 V
A13-1 (-SL) - Body ground	Ignition switch ON	Below 1 V

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

(e) Using a service wire, connect terminals 30 (+SL) and 28 (-SL) of connector B.

NOTICE:

Do not forcibly insert the service wire into the terminals of the connector when connecting a service wire.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A13-2 (+SL) - A13-1 (-SL)	Always	Below 1 Ω

(g) Disconnect the service wire from connector B.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A13-2 (+SL) - A13-1 (-SL)	Always	1 MΩ or higher
A13-2 (+SL) - Body ground	Always	1 MΩ or higher
A13-1 (-SL) - Body ground	Always	1 MΩ or higher

GO TO STEP 5

4.	CHECK FRONT AIRBAG SENSOR LH

(a) Connect the connectors to the center airbag sensor.

(b) Interchange the front airbag sensor LH with RH and connect the connectors to them.

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

(e) Clear the DTCs stored in memory (See page
).

(f) Turn the ignition switch off.

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

(h) Check for DTCs (See page ).

Result

Result	Proceed to
DTC B1617 or B1618 is output	A
DTC B1612 or B1613 is output	B
DTC B1612, B1613, B1617 and B1618 are not output	C

HINT:

Codes other than DTC B1612, B1613, B1617 and B1618 may be output at this time, but they are not related to this check.

Text in Illustration

*1	Front Airbag Sensor RH
*2	Center Airbag Sensor

USE SIMULATION METHOD TO CHECK

REPLACE CENTER AIRBAG SENSOR ASSEMBLY

REPLACE FRONT AIRBAG SENSOR LH

5.	CHECK INSTRUMENT PANEL WIRE (CENTER AIRBAG SENSOR - ENGINE ROOM MAIN WIRE)

(a) Disconnect the instrument panel wire connector from the engine room main wire.

Text in Illustration

*1	Front Airbag Sensor LH	*2	Center Airbag Sensor
*3	Engine Room Main Wire	*4	Instrument Panel Wire
*5	Connector C	*6	Connector B
*7	Service Wire	-	-
*a	Front view of wire harness connector (to Engine Room Main Wire)	*b	Rear view of wire harness connector (to 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
FA4-2 (+SL) - Body ground	Ignition switch ON	Below 1 V
FA4-1 (-SL) - 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) Using a service wire, connect terminals 30 (+SL) and 28 (-SL) of connector B.

NOTICE:

Do not forcibly insert the service wire into the terminals of the connector when connecting a service wire.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
FA4-2 (+SL) - FA4-1 (-SL)	Always	Below 1 Ω

(h) Disconnect the service wire from connector B.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
FA4-2 (+SL) - FA4-1 (-SL)	Always	1 MΩ or higher
FA4-2 (+SL) - Body ground	Always	1 MΩ or higher
FA4-1 (-SL) - Body ground	Always	1 MΩ or higher

REPLACE ENGINE ROOM MAIN WIRE

REPLACE INSTRUMENT PANEL WIRE

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