Seat Temperature Element: Testing and Inspection

2. DIAGNOSIS CHART

3. CHECK SEAT HEATER FUSE
Remove the seat heater fuse and inspect visually.

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 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 step 2.
- No -> Check the harness between the seat heater switch and fuse.

2. CHECK 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 step 3.
- No -> Repair the harness.

3. CHECK 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 normal.
- No -> Repair the harness.

5. CHECK THERMISTOR CIRCUIT
1. Disconnect the seat heater switch connector.
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 ohm to 200 K ohms ?
- Yes -> The thermistor circuit is normal.
- No -> The harness or thermistor is faulty.

6. CHECK SEAT HEATER SWITCH
1. CHECK THERMISTOR OUTPUT VOLTAGE
1. Turn the ignition switch to ON.
2. Measure the voltage between the 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 step 2.
- No -> Replace the seat heater switch.

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

Connector & terminal
LHD side seat (AD8) No. 9 (+) - Chassis ground (-):
RHD side seat (AD8) No. 7 (+) - Chassis ground (-):

Does the voltage fluctuate between 12 V <-> 0 V?
- Yes -> The harness or thermistor is faulty, or the heater has an open circuit.
- No -> Replace the seat heater switch.