Disconnect the seat heater unit 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 unit with a new part.
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.