Toyota CH-R Service Manual: Seat Belt Buckle Switch LH Circuit Malfunction (B1656/38)

DESCRIPTION

The seat belt buckle switch LH circuit consists of the airbag sensor assembly and seat belt buckle switch LH (front seat inner belt assembly LH).

DTC B1656/38 is stored when a malfunction is detected in the seat belt buckle switch LH circuit.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Test Mode / Check Mode
B1656/38	Seat Belt Buckle Switch LH Circuit Malfunction	The airbag sensor assembly detects a line short, short to ground or B+, or an open in the seat belt buckle switch LH circuit. Seat belt buckle switch LH malfunction Airbag sensor assembly malfunction	Floor wire Seat belt buckle switch LH (Front seat inner belt assembly LH) Airbag sensor assembly	Does not apply to test/check mode

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

After turning the ignition switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.

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PROCEDURE

1.	CHECK CONNECTORS

(a) Turn the ignition switch off.

(b) Disconnect the cable from the negative (-) battery terminal.

CAUTION:

Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

(c) Check that the connectors are properly connected to the airbag sensor assembly and front seat inner belt assembly LH.

OK:

The connectors are properly connected.

HINT:

If the connectors are not properly connected, reconnect the connectors and proceed to the next inspection.

(d) Disconnect the connectors from the airbag sensor assembly and front seat inner belt assembly LH.

(e) Check that the terminals of the connectors are not deformed or damaged.

OK:

The terminals are not deformed or damaged.

NG

REPLACE FLOOR WIRE

OK

2.	CHECK FLOOR WIRE (OPEN)

(a) Using a service wire, connect terminals 10 (LBE+) and 18 (LBE-) of connector B. NOTICE: Do not forcibly insert the service wire into the terminals of the connector when connecting the wire.

*1 Front Seat Inner Belt Assembly LH *2 Airbag Sensor Assembly *3 Floor Wire *4 Service Wire *a Front view of wire harness connector (to Airbag Sensor Assembly) *b Front view of wire harness connector (to Front Seat Inner Belt Assembly LH)

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
M101-2 (LBE+) - M101-1 (LBE-)	Always	Below 1 Ω

(c) Disconnect the service wire from connector B.

NG

REPLACE FLOOR WIRE

OK

3.	CHECK FLOOR WIRE (SHORT)

(a) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition M101-2 (LBE+) - M101-1 (LBE-) Always 1 MΩ or higher

*1 Front Seat Inner Belt Assembly LH *2 Airbag Sensor Assembly *3 Floor Wire *a Front view of wire harness connector (to Front Seat Inner Belt Assembly LH)

NG

REPLACE FLOOR WIRE

OK

4.	CHECK FLOOR WIRE (SHORT TO B+)

(a) Connect the cable to the negative (-) battery terminal.

*1 Front Seat Inner Belt Assembly LH *2 Airbag Sensor Assembly *3 Floor Wire *a Front view of wire harness connector (to Front Seat Inner Belt Assembly LH)

(b) Turn the ignition switch on (IG).

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
M101-2 (LBE+) - Body ground	Ignition switch on (IG)	Below 1 V
M101-1 (LBE-) - Body ground	Ignition switch on (IG)	Below 1 V

(d) Turn the ignition switch off.

(e) Disconnect the cable from the negative (-) battery terminal.

CAUTION:

Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

NG

REPLACE FLOOR WIRE

OK

5.	CHECK FLOOR WIRE (SHORT TO GROUND)

(a) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition M101-2 (LBE+) - Body ground Always 1 MΩ or higher M101-1 (LBE-) - Body ground Always 1 MΩ or higher

*1 Front Seat Inner Belt Assembly LH *2 Airbag Sensor Assembly *3 Floor Wire *a Front view of wire harness connector (to Front Seat Inner Belt Assembly LH)

NG

REPLACE FLOOR WIRE

OK

6.

CHECK DTC

(a) Connect the connectors to the airbag sensor assembly and front seat inner belt assembly LH.

*1 Front Seat Inner Belt Assembly LH *2 Airbag Sensor Assembly

(b) Connect the cable to the negative (-) battery terminal.

(c) Clear the DTCs stored in memory.

Click here

Body Electrical > SRS Airbag > Clear DTCs

(d) Turn the ignition switch off.

(e) Turn the ignition switch on (IG), and wait for at least 60 seconds.

(f) Check for DTCs.

Click here

Body Electrical > SRS Airbag > Trouble Codes

OK:

DTC B1656/38 is not output.

HINT:

Codes other than DTC B1656/38 may be output at this time, but they are not related to this check.

OK

USE SIMULATION METHOD TO CHECK

NG

7.	CHECK FRONT SEAT INNER BELT ASSEMBLY LH

(a) Turn the ignition switch off.

*1 Front Seat Inner Belt Assembly LH *2 Airbag Sensor Assembly

(b) Disconnect the cable from the negative (-) battery terminal.

CAUTION:

Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

(c) Replace the front seat inner belt assembly LH with a known good one.

Click here

HINT:

Perform the following inspection using known good parts from another vehicle if possible.

(d) Connect the cable to the negative (-) battery terminal.

(e) Clear the DTCs stored in memory.

Click here

Body Electrical > SRS Airbag > Clear DTCs

(f) Turn the ignition switch off.

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

(h) Check for DTCs.

Click here

Body Electrical > SRS Airbag > Trouble Codes

OK:

DTC B1656/38 is not output.

HINT:

Codes other than DTC B1656/38 may be output at this time, but they are not related to this check.

(i) Turn the ignition switch off.

(j) Disconnect the cable from the negative (-) battery terminal.

CAUTION:

Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

(k) Restore the front seat inner belt assembly LH that was installed for testing to its original location.

Click here

OK

REPLACE FRONT SEAT INNER BELT ASSEMBLY LH

NG

REPLACE AIRBAG SENSOR ASSEMBLY