Toyota Sienna Service Manual: SRS Warning Light Remains ON

DESCRIPTION

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

When the SRS is normal, the SRS warning light comes on for approximately 6 seconds after the ignition switch is turned from the LOCK position to ON position, 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, the DTC is displayed by blinking of the SRS warning light.

The SRS is equipped with a voltage-increase circuit (DC-DC converter) in the center 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 center 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 center airbag sensor assembly to the combination meter assembly through the multiplex communication system.

WIRING DIAGRAM

INSPECTION PROCEDURE

1 CHECK MULTIPLEX COMMUNICATION SYS

1. Check if the multiplex communication DTC is output.

HINT: The center airbag sensor assembly of this system is connected to the multiplex communication system.

Therefore, before starting troubleshooting, make sure to check that there is no trouble in the multiplex communication system.

OK: The Multiplex communication system DTC is not output

2 CHECK BATTERY

1. Measure the voltage of the battery.

Standard voltage: 11 to 14 V

3 CHECK CONNECTORS

1. Turn the ignition switch to the LOCK position.
2. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
3. Check that the connectors are properly connected to the center airbag sensor assembly and combination meter assembly.

OK: The connectors are properly connected.

4 CHECK WIRE HARNESS (SOURCE VOLTAGE OF CENTER AIRBAG SENSOR ASSEMBLY)

1. Disconnect the connectors from the center airbag sensor assembly.
2.  Connect the negative (-) terminal cable to the battery, and wait for at least 2 seconds.
3.  Turn the ignition switch to the ON position.
4.  Operate all components of the electrical system (defogger, wipers, headlight, heater blower, etc.).
5.  Measure the voltage according to the value(s) in the table below.

Standard voltage

6. Turn the ignition switch to the LOCK position.
7.  Measure the resistance according to the value(s) in the table below.

Standard resistance

5 CHECK WIRE HARNESS (SOURCE VOLTAGE OF COMBINATION METER ASSEMBLY)

1. Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
2.  Disconnect the connector from the combination meter assembly.
3.  Connect the negative (-) terminal cable to the battery, and wait for at least 2 seconds.
4. Turn the ignition switch to the ON position.
5.  Measure the voltage according to the value(s) in the table below.

Standard voltage

6. Turn the ignition switch to the LOCK position.
7.  Measure the resistance according to the value(s) in the table below.

Standard resistance

6 CHECK SRS WARNING LIGHT

1. Turn the ignition switch to the LOCK position.
2.  Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
3.  Connect the connector to the combination meter assembly.
4.  Connect the negative (-) terminal cable to the battery, and wait for at least 2 seconds.
5.  Turn the ignition switch to the ON position.
6.  Check the SRS warning light condition.

OK: After the primary check period, SRS warning light goes off for approximately 10 seconds, and remains on.

HINT: The primary check period shows approximately 6 seconds after the ignition switch is turned to the ON position.

REPLACE CENTER AIRBAG SENSOR ASSEMBLY