Toyota Tundra Service Manual: SRS Warning Light Remains ON

DESCRIPTION

The SRS warning light is located in the combination meter assembly.

When the SRS is normal, the SRS warning light comes on for approximately 6 seconds after the engine switch is turned from off on (IG), and then goes off automatically.

If there is a malfunction in the SRS, the SRS warning light comes on to inform the driver of a problem.

When terminals TC and CG of the DLC3 are connected, DTCs are output by the blinking of the SRS warning light.

The SRS is equipped with a voltage-increase circuit (DC-DC converter) in the airbag sensor assembly in case the source voltage drops.

When the battery voltage drops, the voltage-increase circuit (DC-DC converter) functions to increase the voltage of the SRS to normal voltage.

A malfunction in this circuit is not recorded in the airbag sensor assembly. The SRS warning light automatically goes off when the source voltage returns to normal.

The signal to illuminate the SRS warning light is transmitted from the airbag sensor assembly to the combination meter assembly through the CAN communication system.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

• After turning the engine 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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• When disconnecting the cable from the negative (-) battery terminal while performing repairs, some systems need to be initialized after the cable is reconnected.

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• Inspect the fuses for circuits related to this system before performing the following procedure.
• When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.

PROCEDURE

(a) Turn the engine switch on (IG) and check the SRS warning light condition.

HINT:

The primary check is performed for approximately 6 seconds after the engine switch is turned on (IG).

B

GO TO STEP 6

A

(a) Measure the battery voltage.

Standard voltage:

11 to 14 V

HINT:

It may be possible to tell whether the battery is discharged by operating the horn.

If the voltage is below 11 V, recharge or replace the battery before proceeding to the next step.

NG

REPLACE OR RECHARGE BATTERY

OK

(a) Turn the engine switch off.

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

(c) Check that the connector is properly connected to the airbag sensor assembly.

OK:

The connector is properly connected.

HINT:

If the connector is not properly connected, reconnect the connector and proceed to the next inspection.

(d) Disconnect the connector from the airbag sensor assembly.

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

OK:

The terminals are not deformed or damaged.

NG

REPLACE INSTRUMENT PANEL WIRE

OK

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

*a Front view of wire harness connector (to Airbag Sensor Assembly)

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

(c) Operate all components of the electrical systems (defogger, wipers, headlights, heater blower, etc.).

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

Standard Voltage:

(e) Turn the engine switch off.

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

Standard Resistance:

NG

REPLACE HARNESS AND CONNECTOR

OK

(a) Turn the engine switch on (IG) and check the SRS warning light condition.

OK:

After the primary check period, the SRS warning light turns off for approximately 10 seconds and then turns back on.

HINT:

The primary check period is approximately 6 seconds after the engine switch is turned on (IG).

OK

REPLACE AIRBAG SENSOR ASSEMBLY

NG

REPLACE COMBINATION METER ASSEMBLY

(a) Check if a CAN communication DTC is output.

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DTCs are output

GO TO CAN COMMUNICATION SYSTEM

DTC is not output

(a) Measure the battery voltage with the engine switch off.

Standard voltage:

11 to 14 V

HINT:

It may be possible to tell whether the battery is discharged by operating the horn.

If the voltage is below 11 V, recharge or replace the battery before proceeding to the next step.

NG

REPLACE OR RECHARGE BATTERY

OK

(a) Turn the engine switch off.

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

(c) Check that the connector is properly connected to the airbag sensor assembly.

OK:

The connector is properly connected.

HINT:

If the connector is not properly connected, reconnect the connector and proceed to the next inspection.

(d) Disconnect the connector from the airbag sensor assembly.

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

OK:

The terminals are not deformed or damaged.

NG

REPLACE INSTRUMENT PANEL WIRE

OK

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

*a Front view of wire harness connector (to Airbag Sensor Assembly)

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

(c) Operate all components of the electrical systems (defogger, wipers, headlights, heater blower, etc.).

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

Standard Voltage:

(e) Turn the engine switch off.

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

Standard Resistance:

NG

REPLACE HARNESS AND CONNECTOR

OK

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

(b) Check that the connector is properly connected to the combination meter assembly.

OK:

The connector is properly connected.

HINT:

If the connector is not properly connected, reconnect the connector and proceed to the next inspection.

(c) Disconnect the connector from the combination meter assembly.

(d) Check that the terminals of the connector are not deformed or damaged.

OK:

The terminals are not deformed or damaged.

NG

REPAIR OR REPLACE CONNECTOR

OK

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

*a Front view of wire harness connector (to Combination Meter Assembly)

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

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

Standard Voltage:

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

Standard Resistance:

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

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

(b) Connect the connector to the combination meter assembly.

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

(d) Turn the engine switch on (IG) and check the SRS warning light condition.

OK:

After the primary check period, the SRS warning light turns off for approximately 10 seconds and then turns back on.

HINT:

The primary check period is approximately 6 seconds after the engine switch is turned on (IG).

OK

REPLACE AIRBAG SENSOR ASSEMBLY

NG

REPLACE COMBINATION METER ASSEMBLY