Disconnect the negative (-) battery terminal.

Remove the audio unit.(Refer to the BE group - "Audio")

Remove the heater and air conditioner controller(A) after loosening 4 screws.

Install the heater and air conditioner controller.

Install the audio.

Connect the battery (-) terminal.

Disconnect the negative (-) battery terminal.

Remove the rear door trim.

(Refer to the BD group - "Rear door")

Disconnect the rear seat heater switch connector(A).

Turn rear seat heater switch ON and check that continuity exists between the terminals.

If there is no continuity, replace the seat heater switch.