Subaru Legacy BN/BS (2015-2019) Service Manual: Inspection

Subaru Legacy BN/BS (2015-2019) Service Manual / Seats / Seat heater system / Inspection

1. WIRING DIAGRAM

Refer to “Seat Heater System” in the wiring diagram.

• Front: Seat Heater System > WIRING DIAGRAM

• Rear: Seat Heater System > WIRING DIAGRAM

2. DIAGNOSTIC CHART

Symptoms	Repair order
Front seat heater does not operate.	Refer to “HVAC SYSTEM (DIAGNOSTICS)”. Basic Diagnostic Procedure > PROCEDURE
Rear seat heater does not operate.	1. Check the fuse. Seat Heater System > INSPECTION
	2. Check the seat heater system power supply and ground circuit. Seat Heater System > INSPECTION
	3. Check the seat heater module. Seat Heater System > INSPECTION
	4. Check the rear seat heater switch. Seat Heater System > INSPECTION
	5. Check the rear seat heater control module. Seat Heater System > INSPECTION

3. CHECK SEAT HEATER FUSE

Remove the seat heater fuse, and then visually check.

Is the fuse blown out-

• Yes > Replace the fuse.

• No > Check the power supply and ground circuits.

4. CHECK POWER SUPPLY AND GROUND CIRCUIT

1. Check power supply circuit

(1) Disconnect the seat heater control module harness connector.

(2) Measure the voltage between harness connector terminal and chassis ground.

Connector & terminal

(R49) No. 14 (+) — Chassis ground (−):

Is the voltage 10 V or more-

• Yes > Go to step 2.

• No > Repair or replace the harness.

2. Check power supply circuit

(1) Turn the ignition switch to ON.

(2) Measure the voltage between harness connector terminal and chassis ground.

Connector & terminal

(R49) No. 5 (+) — Chassis ground (−):

Is the voltage 10 V or more-

• Yes > Go to step 3.

• Repair or replace the harness.

3. Check ground circuit

Measure the resistance between harness connector terminal and chassis ground.

Connector & terminal

(R49) No. 7 — Chassis ground:

(R138) No. 9 — Chassis ground:

Is the resistance less than 10 --

• Yes > Go to step 4.

• No > Repair the harness.

4. Check harness

Measure the resistance between seat heater control module terminal and seat heater switch - rear terminal.

Connector & terminal

(R53) No. 14 — (R138) No. 1:

(R53) No. 16 — (R138) No. 6:

(R53) No. 6 — (R138) No. 2:

(R53) No. 4 — (R138) No. 5:

(R53) No. 2 — (R138) No. 13:

(R53) No. 8 — (R138) No. 4:

Is the resistance less than 10 --

• Yes > Go to step 5.

• No > Repair the harness.

5. Check seat heater module (rear)

Check the seat heater module (rear) as a single part.

Connector & terminal

(R49) No. 7 — Chassis ground:

(R138) No. 9 — Chassis ground:

Is the inspection result normal-

• Yes > Replace the seat heater switch - rear or seat heater control module.

• No > Replace the seat heater module (rear).

5. SEAT HEATER MODULE (REAR)

1. Disconnect the seat heater unit connector, and check the continuity between terminals of connector.

Connector & terminal

Seat cushion:

LH side No. 4 — No. 3:
RH side No. 2 — No. 1:

Backrest LH:

No. 4 — No. 3:

Backrest RH:

No. 4 — No. 3:

Inspection conditions

Standard

Heater temperature

20°C (68°F)

Seat cushion

Approx. 4.7 -

Backrest

Approx. 7.46 -

2. If no continuity exists, replace the seat heater module with a new part.

6. CHECK REAR SEAT HEATER SWITCH

1. Remove the rear seat heater switch and measure the resistance between switch terminals.

Preparation tool:

Circuit tester

Terminal No.	Inspection conditions	Standard
4-9	Switch OFF	1 M- or more
4-9	Switch ON	Less than 1 -
2-9	Switch OFF	1 M- or more
2-9	Switch ON	Less than 1 -

NOTE:

If the light does not illuminate properly even though the continuity check result is normal, replace the switch.

2. Apply battery voltage between the connector terminals to check lighting condition of illumination inside the switch.

Terminal No.	Inspection conditions	Standard
11 (+) — 10 (−)	Apply battery voltage.	Light ON

3. Replace the rear seat heater switch if the inspection result is not within the standard value.

7. CHECK REAR SEAT HEATER CONTROL MODULE

1. Disconnect the connector of rear seat heater control module.

2. Check the continuity between the connectors.

Connector & terminal

5 — 7

14 — 7

Is there continuity-

• Yes > Repair or replace the harness.

• No > Replace the rear seat heater control module.

Removal

1. SEAT HEATER MODULE - FRONT1. Remove the front seats. Front Seat > REMOVAL2. Remove the backrest cover of front seat and seat cushion cover. Front Seat > DISASSEMBLY3. Remove the seat heater modul ...

Installation

1. SEAT HEATER MODULE - FRONT1. Affix the seat heater module - front to the pad assembly.CAUTION:• If the cover - front cushion is removed, make sure to replace the hang wire on the cover - fron ...

Other materials:

Selecting an audio source
Press the AUDIO/TUNE knob. Select the desired source. Example: Source select screen NOTE If the audio control screen appears, select the "Source" key on the audio screen or press the AUDIO/TUNE knob again. When you push the AUDIO/TUNE knob while any scr ...