The Steering Heater Does Not Operate

1. Disconnect the ground terminal from battery sensor and wait for 60 seconds or more. Ref. to REPAIR CONTENTS>NOTE>BATTERY .
2. Disconnect the connector between steering roll connector and steering heater unit.
3. Connect the ground terminal to the battery sensor and turn the ignition switch to ON.
4. Measure the steering roll connector voltage.

   Connector & terminal 

   (ST12) No. 4 (+) - No. 3 (-)

Is the voltage 10 - 14 V?

Yes:  Go to  2.

No: Go to  8.

Check the steering heater switch. Ref. to POWER ASSISTED SYSTEM (POWER STEERING)>Steering Wheel>INSPECTION>STEERING HEATER SWITCH .

Is the steering heater switch OK?

Yes:  Go to  3.

No:  Replace the steering heater switch. Ref. to POWER ASSISTED SYSTEM (POWER STEERING)>Steering Wheel>DISASSEMBLY .

Check the steering heater unit. Ref. to POWER ASSISTED SYSTEM (POWER STEERING)>Steering Heater System>ELECTRICAL SPECIFICATION>STEERING HEATER UNIT .

Is the steering heater unit OK?

Yes:  Go to  4.

No:  Replace the steering heater unit. Ref. to POWER ASSISTED SYSTEM (POWER STEERING)>Steering Wheel>DISASSEMBLY .

Check the steering wheel. Ref. to POWER ASSISTED SYSTEM (POWER STEERING)>Steering Wheel>INSPECTION>STEERING WHEEL HEATER .

Is the steering wheel OK?

Yes:  Go to  5.

No:  Replace the steering wheel. Ref. to POWER ASSISTED SYSTEM (POWER STEERING)>STEERING WHEEL .

Check the harness between steering roll connector and steering heater unit.

Connector & terminal 

(ST11) No. 3 - (ST14) No. 1:

(ST11) No. 4 - (ST14) No. 4:

Is harness normal?

Yes:  Go to  6.

No:  Repair or replace the harness.

Check the harness between steering heater switch and steering roll connector.

Connector & terminal 

(ST9) No. 1 - (ST11) No. 4:

Is harness normal?

Yes:  Go to  7.

No:  Repair or replace the harness.

Check the harness between steering heater switch and steering heater unit.

Connector & terminal 

(ST9) No. 2 - (ST14) No. 3:

(ST9) No. 4 - (ST14) No. 2:

Is harness normal?

Yes:  Go to  8.

No:  Repair or replace the harness.

Check the steering roll connector. Ref. to AIRBAG SYSTEM>Roll Connector>INSPECTION .

Is the result of inspection OK?

Yes:  Go to  9.

No:  Replace the steering roll connector. Ref. to AIRBAG SYSTEM>ROLL CONNECTOR .

Measure the resistance between connector of steering roll connector and body ground and between relay holder and body ground.

Connector & terminal 

(i289) No. 2 - Chassis ground:

(i280) No. 3 - Chassis ground:

Is the resistance less than 10 Ω?

Yes:  Go to  10.

No:  Repair or replace the harness.

Check the harness between relay holder and steering roll connector.

Connector & terminal 

(i280) No. 1 - (i289) No. 4:

Is harness normal?

Yes:  Go to  11.

No:  Repair or replace the harness.

1. Turn the ignition switch to OFF.
2. Check the fuse No. 22 in the fuse & relay box.

Is the fuse OK?

Yes:  Go to  12.

No:  Replace the fuse.

Check the steering heater relay. Ref. to POWER ASSISTED SYSTEM (POWER STEERING)>RELAY AND FUSE .

Is the steering heater relay OK?

Yes:  Go to  13.

No:  Replace the steering heater relay.

Measure the battery voltage.

Is the battery OK?

Yes:  It is possible that temporary poor contact occurs. Restore the parts and check it again.

No:  Check the battery. Ref. to STARTING/CHARGING SYSTEMS (H4DOTC)>Battery>INSPECTION .