Seat Heater On One Side (Backrest Side Or Cushion Side) Does Not Operate

Trouble symptom:

When the seat heater is activated, the seat heater on the backrest side operates, but the one on the cushion side does not operate.
When the seat heater is activated, the seat heater on the cushion side operates, but the one on the backrest side does not operate.

Trouble causes:

Seat ventilation control module failure
A/C control module failure
Seat ventilation circuit failure
Seat heater circuit failure
Center information display failure
Cockpit control module failure
Heater failure

Wiring diagram:

Seat ventilation system Ref. to WIRING SYSTEM>SEAT VENTILATION SYSTEM>WIRING DIAGRAM .

Seat heater system Ref. to WIRING SYSTEM>SEAT HEATER SYSTEM>WIRING DIAGRAM .

G13630739

Courtesy of SUBARU OF AMERICA, INC.

G13630742

Courtesy of SUBARU OF AMERICA, INC.

CAUTION: Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to VENTILATION SEAT (DIAGNOSTICS)>General Description>CAUTION .

CHECK CONNECTOR .
1. Turn the ignition switch to OFF.
2. Check malfunctions (terminal bends, connection status, etc.) of the seat ventilation control module connector (St41), A/C control module connectors (i107) (i 108), seat connectors (L57) (R57), coupling connectors (B43) (L51) (R51), and heater connectors (St27) (St28).
  NOTE: Perform the inspection for the faulty seat.
  
  Is the check result OK?
  
  Yes: Go to 2 .
  
  No: Repair the connector.
CHECK HARNESS (OPEN CIRCUIT) .
1. Disconnect the seat connectors (St1) (St2) and seat heater connectors (St27) (St28) only for the driver's side or passenger's side seat that has portions not functioning properly.
2. Using the tester, measure the resistance between terminals.
  NOTE: Perform the inspection for the faulty seat.
  
  Connector and terminal
  
  Driver's side
  
  (St28) No. 1 - (St2) No. 9:
  
  (St28) No. 2 - (St2) No. 15:
  
  (St28) No. 3 - (St2) No. 16:
  
  (St28) No. 4 - (St2) No. 10:
  
  Passenger's side
  
  (St27) No. 1 - (St1) No. 9:
  
  (St27) No. 2 - (St1) No. 15:
  
  (St27) No. 3 - (St1) No. 16:
  
  (St27) No. 4 - (St1) No. 10:
  
  Is the resistance less than 5 Ω?
  
  Yes: Replace the pad assembly - front seat cushion or the pad assembly - front seat backrest that is not functioning properly. Ref. to SEATS>SEAT HEATER SYSTEM .
  
  No: Repair or replace the open circuit of harness.