Toyota Tacoma (2015-2018) Service Manual: Short in Driver Side Knee Airbag Squib Circuit (B1860/64-B1863/64)

DESCRIPTION

The driver side knee airbag squib circuit consists of the airbag sensor assembly and lower No. 1 instrument panel airbag assembly.

The airbag sensor assembly uses this circuit to deploy the airbag when deployment conditions are met.

These DTCs are stored when a malfunction is detected in the driver side knee airbag squib circuit.

DTC No.	DTC Detection Condition	Trouble Area
B1860/64	The airbag sensor assembly receives a line short circuit signal in the driver side knee airbag squib circuit during primary check. Driver side knee airbag squib malfunction Airbag sensor assembly malfunction	Instrument panel wire Lower No. 1 instrument panel airbag assembly (Driver side knee airbag squib) Airbag sensor assembly
B1861/64	The airbag sensor assembly receives an open circuit signal in the driver side knee airbag squib circuit. Driver side knee airbag squib malfunction Airbag sensor assembly malfunction
B1862/64	The airbag sensor assembly receives a short circuit to ground signal in the driver side knee airbag squib circuit. Driver side knee airbag squib malfunction Airbag sensor assembly malfunction
B1863/64	The airbag sensor assembly receives a short circuit to B+ signal in the driver side knee airbag squib circuit. Driver side knee airbag squib malfunction Airbag sensor assembly malfunction

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 (See page ).

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 lower No. 1 instrument panel airbag assembly and airbag sensor assembly.

OK:

The connectors are properly connected.

HINT:

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

(d) Disconnect the connectors from the lower No. 1 instrument panel airbag assembly and airbag sensor assembly.

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

OK:

The terminals are not deformed or damaged.

(f) Check that the instrument panel wire connector (on the lower No. 1 instrument panel airbag assembly side) is not damaged.

OK:

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

(g) Check that the short spring for the instrument panel wire with the activation prevention mechanism are not deformed or damaged.

OK:

The short spring is not deformed or damaged.

Text in Illustration

*1	Driver Side Knee Airbag Squib
*2	Airbag Sensor Assembly
*3	Instrument Panel Wire

NG

REPLACE INSTRUMENT PANEL WIRE

OK

2.	CHECK LOWER NO. 1 INSTRUMENT PANEL AIRBAG ASSEMBLY (DRIVER SIDE KNEE AIRBAG SQUIB)

(a) Connect the connector to the airbag sensor assembly.

(b) Connect SST (resistance 2.1 Ω) to connector C.

CAUTION:

Never connect the tester to the lower No. 1 instrument panel airbag assembly (driver side knee airbag squib) for measurement, as this may lead to a serious injury due to airbag deployment.

SST: 09843-18061

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

(d) Clear the DTCs stored in memory (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 B1860/64, B1861/64, B1862/64 or B1863/64 is not output.

HINT:

Codes other than DTCs B1860/64, B1861/64, B1862/64 and B1863/64 may be output at this time, but they are not related to this check.

(h) Turn the ignition switch off.

(i) 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.

(j) Disconnect SST from connector C.

Text in Illustration

*1	Driver Side Knee Airbag Squib
*2	Airbag Sensor Assembly
*a	Front view of wire harness connector (to Lower No. 1 Instrument Panel Airbag Assembly)

OK

REPLACE LOWER NO. 1 INSTRUMENT PANEL AIRBAG ASSEMBLY

NG

3.	CHECK INSTRUMENT PANEL WIRE

(a) Disconnect the instrument panel wire from the airbag sensor assembly.

(b) Check for a short to B+ in the circuit.

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

(2) Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
L5-1 (DK+) - Body ground	Ignition switch ON	Below 1 V
L5-2 (DK-) - Body ground	Ignition switch ON	Below 1 V

(4) Turn the ignition switch off.

(5) 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 for an open in the circuit.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
L5-1 (DK+) - L5-2 (DK-)	Always	Below 1 Ω

(d) Check for a short to ground in the circuit.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
L5-1 (DK+) - Body ground	Always	1 MΩ or higher
L5-2 (DK-) - Body ground	Always	1 MΩ or higher

(e) Check for a short in the circuit.

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

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
L5-1 (DK+) - L5-2 (DK-)	Always	1 MΩ or higher

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

Text in Illustration

*1	Driver Side Knee Airbag Squib
*2	Airbag Sensor Assembly
*3	Instrument Panel Wire
*a	Front view of wire harness connector (to Lower No. 1 Instrument Panel Airbag Assembly)

NG

REPLACE INSTRUMENT PANEL WIRE

OK

4.

CHECK DTC

(a) Connect the connectors to the lower No. 1 instrument panel airbag assembly and airbag sensor assembly.

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

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

(d) Clear the DTCs stored in memory (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 B1860/64, B1861/64, B1862/64 or B1863/64 is not output.

HINT:

Codes other than DTCs B1860/64, B1861/64, B1862/64 and B1863/64 may be output at this time, but they are not related to this check.

Text in Illustration

*1	Lower No. 1 Instrument Panel Airbag Assembly
*2	Airbag Sensor Assembly

OK

USE SIMULATION METHOD TO CHECK

NG

REPLACE AIRBAG SENSOR ASSEMBLY