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.

    Click here

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

    Click here

  • 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

1.

CHECK SRS WARNING LIGHT OPERATION

(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).

Result

Proceed to

After the primary check period, the SRS warning light remains on.

A

After the primary check period, the SRS warning light goes off and comes on again.

B

B

GO TO STEP 6

A

2.

CHECK BATTERY

(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

3.

CHECK CONNECTOR

(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

4.

CHECK HARNESS AND CONNECTOR (AIRBAG SENSOR ASSEMBLY - BATTERY AND BODY GROUND)

(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:

Tester Connection

Switch Condition

Specified Condition

J177-36 (IG2) - Body ground

Engine switch on (IG)

8 to 16 V

(e) Turn the engine switch off.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J177-33 (E1) - Body ground

Always

Below 1 Ω

J177-32 (E2) - Body ground

Always

Below 1 Ω

NG

REPLACE HARNESS AND CONNECTOR

OK

5.

CHECK SRS WARNING LIGHT (SHORT TO GROUND)

(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

6.

CHECK CAN COMMUNICATION SYSTEM

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

Click here

DTCs are output

GO TO CAN COMMUNICATION SYSTEM

DTC is not output

7.

CHECK BATTERY

(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

8.

CHECK CONNECTOR

(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

9.

CHECK HARNESS AND CONNECTOR (AIRBAG SENSOR ASSEMBLY - BATTERY AND BODY GROUND)

(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:

Tester Connection

Switch Condition

Specified Condition

J177-36 (IG2) - Body ground

Engine switch on (IG)

8 to 16 V

(e) Turn the engine switch off.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J177-33 (E1) - Body ground

Always

Below 1 Ω

J177-32 (E2) - Body ground

Always

Below 1 Ω

NG

REPLACE HARNESS AND CONNECTOR

OK

10.

CHECK CONNECTOR

(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

11.

CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - BATTERY AND BODY GROUND)

(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:

Tester Connection

Switch Condition

Specified Condition

J28-2 (IG+) - Body ground

Engine switch on (IG)

11 to 14 V

J28-1 (B) - Body ground

Engine switch off

11 to 14 V

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J28-24 (ES) - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

12.

CHECK SRS WARNING LIGHT

(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

    SRS Warning Light does not Come ON

    System Description

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