Seat Heater Level Does Not Change (Display Changes, But Operation Does Not Change)

Trouble symptom:

When the seat heater switch is touched, the display on the center information display changes, but the operation mode does not change.

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

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

Courtesy of SUBARU OF AMERICA, INC.

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 DTC .
1. Turn the ignition switch to ON.
2. Read the following DTCs using Subaru Select Monitor. Ref. to Ventilation Seat (Diagnostics)>Diagnostic Trouble Code (DTC) . Ref. to BODY CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) . Ref. to AIR CONDITIONER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) . Ref. to COCKPIT CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
  - Ventilation Seat
  - Body Control
  - Air Conditioner
  - Cockpit Control
  Are any DTCs displayed?
  
  Yes: Perform the diagnosis for the displayed DTCs. Ref. to Ventilation Seat (Diagnostics)>Diagnostic Trouble Code (DTC) . Ref. to BODY CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) . Ref. to AIR CONDITIONER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) . Ref. to COCKPIT CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
  
  No: Go to 2 .
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).
  Is the check result OK?
  
  Yes: Go to 3 .
  
  No: Repair the connector.
CHECK CAN COMMUNICATION LINE .
Inspect LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

Is the check result OK?

Yes: Go to 4 .

No: Perform the inspection according to the diagnosis for LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .
CHECK SEAT HEATER .
1. Connect all connectors.
2. Turn the ignition switch to ON.
3. Start the engine.
4. Using the Subaru Select Monitor, check the following items in the [Active Test] of [Ventilation Seat]. Ref. to Ventilation Seat (Diagnostics)>Active Test .
  - Driver's Seat Heater
  - Passenger's Seat Heater
  Does the seat heater operate properly?
  
  Yes: Perform the inspection according to the [Cockpit Control] diagnosis. Ref. to COCKPIT CONTROL (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .
  
  No: Replace the seat ventilation control module. Ref. to SEATS>SEAT VENTILATION SYSTEM .