Toyota 4Runner: Lost Communication with Rear Floor Airbag Sensor RH (B1676/85,B1677/85)

Toyota 4Runner Service Manual / Vehicle Interior / Supplemental Restraint Systems / Airbag System / Lost Communication with Rear Floor Airbag Sensor RH (B1676/85,B1677/85)

DESCRIPTION

HINT:

"Rear floor airbag sensor RH" refers to the rear floor side airbag sensor.

The rear floor side airbag sensor circuit consists of the center airbag sensor and rear floor side airbag sensor.
The rear floor side airbag sensor detects impacts to the vehicle and sends signals to the center airbag sensor to determine if the airbag should be deployed.
DTC B1676/85 or B1677/85 is stored when a malfunction is detected in the rear floor side airbag sensor circuit.

DTC Code	DTC Detection Condition	Trouble Area
B1676/85	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 rear floor side airbag sensor circuit for 2 seconds. A rear floor side airbag sensor malfunction. A center airbag sensor malfunction.	Floor wire Rear floor side airbag sensor Center airbag sensor assembly
B1677/85	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 rear floor side airbag sensor circuit for 2 seconds. A rear floor side airbag sensor malfunction. A center airbag sensor malfunction.	Floor wire Rear floor side airbag sensor 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 rear floor side airbag sensor.

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

OK:

The connectors are not deformed or damaged.

Text in Illustration

*1	Rear Floor Side Airbag Sensor
*2	Center Airbag Sensor

REPLACE FLOOR WIRE

3.	CHECK FLOOR WIRE (CENTER AIRBAG SENSOR - REAR FLOOR SIDE AIRBAG SENSOR)

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

Text in Illustration

*1	Rear Floor Side Airbag Sensor	*2	Center Airbag Sensor
*3	Floor Wire	*4	Connector C
*5	Connector B	*6	Service Wire
*a	Front view of wire harness connector (to Rear Floor Side Airbag Sensor)	*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
N6-2 (BER+) - Body ground	Ignition switch ON	Below 1 V
N6-1 (BER-) - 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 21 (BDR+) and 22 (BDR-) 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
N6-2 (BER+) - N6-1 (BER-)	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
N6-2 (BER+) - N6-1 (BER-)	Always	1 MΩ or higher
N6-2 (BER+) - Body ground	Always	1 MΩ or higher
N6-1 (BER-) - Body ground	Always	1 MΩ or higher

REPLACE FLOOR WIRE

4.	CHECK REAR FLOOR SIDE AIRBAG SENSOR

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

(b) Temporarily replace the rear floor side airbag sensor with a new one.

(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 ).

OK:

DTC B1676 and B1677 are not output.

HINT:

Codes other than DTC B1676 and B1677 may be output at this time, but they are not related to this check.

Text in Illustration

*1	Rear Floor Side Airbag Sensor
*2	Center Airbag Sensor

REPLACE REAR FLOOR SIDE AIRBAG SENSOR

REPLACE CENTER AIRBAG SENSOR ASSEMBLY

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