Seat Temperature Element: Testing and Inspection

SEAT HEATER SYSTEM

INSPECTION

1. WIRING DIAGRAM

Electrical Diagrams

2. DIAGNOSTIC CHART

Diagnostic Chart:

3. CHECK SEAT HEATER FUSE

Remove the seat heater fuse, and then visually check.

Is the fuse blown out?
- Yes ->Replace the fuse.
- No ->Check the power supply and ground circuit.

4. CHECK POWER SUPPLY AND GROUND CIRCUIT

1. CHECK THE POWER SUPPLY CIRCUIT
1. Disconnect the seat heater switch.
2. Turn the ignition switch to ON.
3. Measure the voltage between harness connector terminal and chassis ground.

Connector & terminal
(AD8) No. 12 (+) - Chassis ground (-):

Is the voltage 12 V or more?
- Yes -> Go to symptom 2.
- No -> Check the harness between seat heater switch and fuse.

2. CHECK THE GROUND CIRCUIT

Measure the resistance between harness connector terminal and chassis ground.

Connector & terminal
(AD8) No. 2 - Chassis ground:

Is the resistance less than 10 Ohms?
- Yes -> Go to symptom 3.
- No -> Repair the harness.

3. CHECK THE GROUND CIRCUIT

Measure the resistance between harness connector terminals.

Connector & terminal
(AD8) No. 1 - (AD8) No. 2:
(AD8) No. 3 - (AD8) No. 2:

Is the resistance less than 10 Ohms?
- Yes -> The power supply and ground circuit are OK.
- No -> Repair the harness.

5. CHECK THERMISTOR CIRCUIT

1. Disconnect the connector of seat heater switch.
2. Measure the resistance between harness connector terminals.

Connector & terminal

Check LHD side
(AD8) No. 8 - (AD8) No. 3:

Check RHD side
(AD8) No. 6 - (AD8) No. 1:

Is the resistance between 1 k Ohms and 200 k Ohms?
- Yes -> Thermistor circuit is normal
- No -> Harness faulty or thermistor faulty

6. CHECK SEAT HEATER SWITCH

1. CHECK THERMISTOR OUTPUT VOLTAGE

1. Turn the ignition switch to ON.
2. Measure the voltage between seat heater switch and chassis ground.

Connector & terminal:

LHD side seat
(AD8) No. 8 (+) - Chassis ground (-):

RHD side seat
(AD8) No. 6 (+) - Chassis ground (-):

Is the voltage 1.5 V or more?
- Yes -> Go to symptom 2.
- No -> Replace the seat heater switch.

2. CHECK OUTPUT VOLTAGE

1. Turn the ignition switch to ON.
2. Measure the voltage between seat heater switch and chassis ground when turning the switch to other than OFF position.

Connector & terminal:

LHD side seat
(AD8) No. 9 (+) - Chassis ground (-):

RHD side seat
(AD8) No. 7 (+) - Chassis ground (-):

Does the voltage repeat 12V and 0V?
- Yes -> Harness faulty, open circuit of heater or thermostat faulty
- No -> Replace the seat heater switch.