Check Interior Light System

WARNING: This page is about a different car, the 2021 Subaru Ascent. However, it is still accessible from the selected car via links, so may be relevant.

Trouble symptom:

Spot map lights and reading lights do not turn on/off in accordance with door open/close operations.

Luggage room light does not turn on/off in accordance with rear gate open/close operations.

CHECK INTERIOR LIGHT ILLUMINATION .
1. Turn the spot map light switch and the luggage room light switch to the DOOR position.
2. Open the doors and the rear gate.
Do the spot map light, reading light and luggage room light illuminate?

Yes : The interior light system is normal.

No : Go to 2.
CHECK THE LIGHTS .
Check the spot map light, reading light and luggage room light.

Are the spot map light, reading light and luggage room light normal?

Yes : Go to 3.

No : Replace the spot map light, reading light and luggage room light.
CHECK CURRENT DATA .
1. Turn the ignition switch to ON.
2. Display the data of [Driver's door SW input], [P-door SW input], [Rear right door SW input], [Rear left door SW input] and [R Gate SW input] using Subaru Select Monitor. Ref. to BODY CONTROL (DIAGNOSTICS)>DATA MONITOR .
Does the display switch between [OFF] <-> [ON] when each door or the rear gate is opened/closed?

Yes : Go to 5.

No : Go to 4.
CHECK SWITCH .
Check the door switch or rear gate latch switch.

Is the door switch or the rear gate latch switch normal?

Yes : Go to 5.

No : Replace the door switch or rear gate latch switch.
CHECK HARNESS .
1. Disconnect the connectors between body integrated unit and door switch and between body integrated unit and rear gate latch switch.
2. Check the harnesses between body integrated unit and door switch and between body integrated unit and rear gate latch switch.
  Connector & terminal
  
  (i171) No. 39 - (R9) No. 2:
  
  (i171) No. 13 - (R12) No. 2:
  
  (i171) No. 14 - (R22) No. 2:
  
  (i171) No. 27 - (R16) No. 2:
  
  (i171) No. 15 - (D46) No. 3:
Is harness normal?

Yes : Go to 6.

No : Repair or replace the harness.
CHECK HARNESS .
Check the harnesses between the connectors of the door switch and rear gate latch switch and the chassis ground.

Connector & terminal

(R9) No. 1 - Chassis ground:

(R12) No. 1 - Chassis ground:

(R22) No. 1 - Chassis ground:

(R16) No. 1 - Chassis ground:

(D46) No. 4 - Chassis ground:

Is harness normal?

Yes : Go to 7.

No : Repair or replace the harness.
CHECK CURRENT DATA .
1. Turn the ignition switch to ON.
2. Display the data of [Map lamp output] and [Luggage/Trunk lamp output] using Subaru Select Monitor. Ref. to BODY CONTROL (DIAGNOSTICS)>DATA MONITOR .
  - Does the display of [Map lamp output] switch between [OFF] <-> [ON] when the door is opened/closed?
  - Does the display of [Luggage/Trunk lamp output] switch between [OFF] <-> [ON] when the rear gate is opened/closed?
Yes : Go to 8.

No : Check the body integrated unit and replace it if defective.
- Inspection: Ref. to BODY CONTROL (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .
- Replacement: Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT .
CHECK FUSE AND RELAY .
1. Turn the ignition switch to OFF.
2. Check F/B fuse No. 26 and O/T ILL RELAY. Ref. to LIGHTING SYSTEM>Relay and Fuse>INSPECTION .
Is the F/B fuse No. 26 and O/T ILL RELAY normal?

Yes : Go to 9.

No : Replace the defective fuse or relay.
CHECK HARNESS .
1. Disconnect the connectors of spot map light, reading light, luggage room light and O/T ILL RELAY.
2. Measure the voltage between each connector and chassis ground.
  Connector & terminal
  
  (B225) No. 36 (+) - Chassis ground (-):
  
  (B225) No. 34 (+) - Chassis ground (-):
  
  (R405) No. 1 (+) - Chassis ground (-):
  
  (R369) No. 1 (+) - Chassis ground (-):
  
  (R370) No. 1 (+) - Chassis ground (-):
  
  (R371) No. 1 (+) - Chassis ground (-):
  
  (R372) No. 1 (+) - Chassis ground (-):
  
  (R141) No. 2 (+) - Chassis ground (-):
Is the voltage 8.5 - 16.5 V?

Yes : Go to 10.

No : Repair or replace the harness.
CHECK HARNESS .
1. Disconnect the connectors of body integrated unit, spot map light, reading light, luggage room light and O/T ILL RELAY.
2. Check the harnesses between each light connector and body integrated unit.
  Connector & terminal
  
  (i171) No. 11 - (B225) No. 35:
  
  (i171) No. 10 - (R405) No. 4:
  
  (i84) No. 9 - (R369) No. 3:
  
  (i84) No. 9 - (R370) No. 3:
  
  (i171) No. 16 - (R371) No. 3:
  
  (i171) No. 16 - (R372) No. 3:
  
  (i84) No. 8 - (R141) No. 1:
Is harness normal?

Yes : Go to 11.

No : Repair or replace the harness.
CHECK HARNESS .
Check the harnesses between spot map light and reading light connectors and chassis ground.

Connector & terminal

(R405) No. 13 - Chassis ground:

(R369) No. 5 - Chassis ground:

(R370) No. 5 - Chassis ground:

(R371) No. 5 - Chassis ground:

(R372) No. 5 - Chassis ground:

Is harness normal?

Yes : Check the body integrated unit and replace it if defective.
- Inspection: Ref. to BODY CONTROL (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .
- Replacement: Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT .
No : Repair or replace the harness.