• AT model and single-range MT model 
• Dual-range MT model
2. DIAGNOSTIC CHART (AT MODEL AND SINGLE-RANGE MT MODEL)
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Symptoms |
Repair order |
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Seat heater does not operate. |
1. Check the fuses. |
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2. Check the power supply and ground circuit for the seat heater system. | |
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3. Check the thermistor circuit. | |
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4. Check the seat heater switch circuit. |
3. CHECK SEAT HEATER FUSE (AT MODEL AND SINGLE-RANGE MT MODEL)
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 (AT MODEL AND SINGLE-RANGE MT MODEL)
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 Ω?
• 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 Ω?
• Yes → The power supply and ground circuit are normal.
• No → Repair the harness.
5. CHECK THERMISTOR CIRCUIT (AT MODEL AND SINGLE-RANGE MT MODEL)
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 KΩ to 200 KΩ?
• Yes → The thermistor circuit is normal.
• No → The harness or thermistor is faulty.
6. CHECK SEAT HEATER SWITCH (AT MODEL AND SINGLE-RANGE MT MODEL)
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.
7. SEAT HEATER MODULE (DUAL-RANGE MT MODEL)
Disconnect the seat heater module connector, and check the continuity between terminals of connector.
Connector & terminal
No. 1 — No. 3:
No. 1 — No. 4:
No. 3 — No. 4:
If no continuity exists, replace the seat heater module with a new part.
8. SEAT HEATER SWITCH (DUAL-RANGE MT MODEL)
Inspect the continuity between the seat heater switch terminals.
Connector & terminal
HI
No. 2 — No. 1:
No. 2 — No. 3:
No. 1 — No. 3:
No. 4 — No. 3:
LOW
No. 2 — No. 4:
No. 2 — No. 3:
No. 4 — No. 3:
If no continuity exists, replace the seat heater switch with a new part.