The Steering Heater Does Not Operate

CHECK POWER SUPPLY INPUT.
1. Disconnect the negative terminal from the battery, and wait for 60 seconds or more.
2. Disconnect the connector between steering roll connector and steering heater unit.
3. Connect the battery ground terminal and turn the ignition switch to ON.
4. Measure the steering roll connector voltage.
Connector & terminal

Heater switch power supply input

(ST12) No. 2 (+) -No. 3 (-):

Heater unit power supply input

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

Is the voltage 10 - 14 V?
- Yes : Go to 2.
- No : Go to 5.
CHECK STEERING HEATER SWITCH.
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 STEERING HEATER UNIT.
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 STEERING WHEEL.
Check the steering wheel. Ref. to POWER ASSISTED SYSTEM (POWER STEERING)>Steering Wheel>INSPECTION>STEERING WHEEL HEATER .

Is the steering wheel OK?
- Yes : It is possible that temporary poor contact occurs. Restore the parts and check it.
- No : Replace the steering wheel. Ref. to POWER ASSISTED SYSTEM (POWER STEERING)>Steering Wheel .
CHECK FUSE.
1. Turn the ignition switch to OFF.
2. Check the fuse No. 33 in the fuse & relay box.
Is the fuse OK?
- Yes : Go to 6.
- No : Replace the fuse.
CHECK RELAY.
Check the steering heater relay. Ref. to POWER ASSISTED SYSTEM (POWER STEERING)>Relay and Fuse .

Is the steering heater relay OK?
- Yes : Go to 7.
- No : Replace the steering heater relay.
CHECK BATTERY VOLTAGE.
Measure the battery voltage.

Is the battery OK?
- Yes : Go to 8.
- No : Check the battery. Ref. to STARTING/CHARGING SYSTEMS(H4DO)>Battery>INSPECTION .
CHECK ROLL CONNECTOR (HEATER).
Measure the resistance between steering roll connectors (heater part). Ref. to COMMUNICATION SYSTEM>Horn Switch>INSPECTION>CHECK ROLL CONNECTOR .

Is the steering roll connector OK?
- Yes : It is possible that temporary poor contact occurs. Restore the parts and check it.
- No : Replace the steering roll connector. Ref. to AIRBAG SYSTEM>Roll Connector .