Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Check With SUBARU Select Monitor
Before performing the inspection, check the following settings.
- Wiper deicer setting - "support". If "no support", set to "support" using customize setting.
- Rear defogger operation mode setting - initial setting or customize setting.
- CHECK BODY INTEGRATED UNIT SETTING
.
- Turn the ignition switch to ON.
- Display the [wiperdeicer] data using Subaru Select Monitor. Ref. to BODY CONTROL (DIAGNOSTICS)>DATA MONITOR
.
Do the vehicle equipment and the settings of body integrated unit match?
Yes: Go to 2.
No: Selecting from the Customize item list, match the [wiperdeicer] settings to the actual vehicle equipment. Ref. to BODY CONTROL (DIAGNOSTICS)>CUSTOMIZE . Check the input of the body integrated unit. Go to 2.
- CHECK INPUT OF BODY INTEGRATED UNIT
.
- Check the operation with rear window defogger switch ON.
- When the customize setting is "Continuous", it is normal if the operation continues for 15 minutes or more.
- When customize setting is "Normal", it is normal if the operation lasts for 15 minutes and then turns OFF.
Does it operate properly?
Yes: Function is normal.
No: Auto A/C: Go to 3.
Manual A/C: Go to 4.
- Check the operation with rear window defogger switch ON.
- CHECK BODY INTEGRATED UNIT
.
Read the DTC of body integrated unit using Subaru Select Monitor.
NOTE:For detailed operation procedures, refer to "Application help".
Is DTC displayed?
Yes: Perform the diagnosis according to the DTC. Ref. to BODY CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>OPERATION .
No: Go to 5.
- CHECK HARNESS
.
- Turn the ignition switch to OFF.
- Disconnect the connector of body integrated unit and rear window defogger switch.
- Check the harness between body integrated unit and rear window defogger switch.
Connector & terminal
(i171) No. 5 - (i88) No. 10:
Is harness normal?
Yes: Go to 5.
No: Repair or replace the harness.
- CHECK FUSE AND RELAY
.
Check the F/B fuse No. 8, M/B fuse No. 35 and wiper deicer relay. Ref. to GLASS/WINDOW/MIRRORS>RELAY AND FUSE>INSPECTION .
Is the check result OK?
Yes: Go to 6.
No: Replace the defective fuse or relay.
- CHECK HARNESS
.
- Remove the wiper deicer relay.
- Measure the voltage between relay holder and chassis ground.
Connector & terminal
(B225) No. 52 (+) - Chassis ground (-):
(B225) No. 54 (+) - Chassis ground (-):
Is the voltage 8.5 - 16.5 V?
Yes: Go to 7.
No: Repair or replace the harness.
- CHECK HARNESS
.
- Remove the wiper deicer relay.
- Disconnect the connector of body integrated unit and wiper deicer.
- Check the harness between relay holder and body integrated unit connector.
- Check the harness between relay holder and wiper deicer connector.
Connector & terminal
Body integrated unit side
(B225) No. 53 - (B281) No. 4:
Wiper deicer side
(B225) No. 55 - (B177) No. 2:
Is harness normal?
Yes: Go to 8.
No: Repair or replace the harness.
- CHECK HARNESS
.
Check the harness between wiper deicer connector and chassis ground.
Connector & terminal
(B177) No. 1 (+) - Chassis ground (-):
Is harness normal?
Yes: Replace the body integrated unit. Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT .
No: Repair or replace the harness.
NO RELATED
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.