2. Disconnect the seat heater, turn it off and check its conductivity at the terminals with a tester. With the switch in the ON position, connect the "b" terminals (green wire) and "c" (blue wire), there must be contact. If not, replace the switch.
Identifying the seat heater connector pins
3. Disconnect the wiring harness connectors under the seat. Check the seat connectors for continuity. There should be continuity between the "W" terminals on the 2-pole and 4-pole connectors, and between the "B" terminals. If not, the heater (or electrical wiring) the seats are faulty.
Checking the continuity of the seat cushion heater contacts
4. Check the seat back heater connector. There should be continuity between the "Y" terminal on the single-pole connector and the "B" terminal on the four-pole connector. If not, the heater or seat back wiring is faulty.
Checking the conductivity of the seat back heater contacts
5. Heating elements can only be replaced completely with the seat cushion or backrest, depending on how it is equipped.