rear defrost will not shut-off

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Nov 4, 2025 | 12:20 PM

morsed4@gmail.com

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Joined: Nov 2025

Posts: 3

rear defrost will not shut-off

After driving in heavy rain, the battery was drained, and the light on the defrost switch was on with the car off. 2004 Ion. Hopefully, someone may have a suggestion.

Thanks

Nov 4, 2025 | 12:57 PM

02 LW300

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Joined: Apr 2015

Posts: 3,229

From: Willamette Valley, Oregon

Troubleshoot the discharged battery first, the rear defroster will probably correct itself. Heavy rain should not be an issue unless you have been driving through deep water and you have missing under body panels.

Nov 4, 2025 | 01:15 PM

morsed4@gmail.com

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Joined: Nov 2025

Posts: 3

Thank you. I will look into this this afternoon.

Nov 4, 2025 | 01:38 PM

derf

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Joined: Jul 2005

Posts: 12,315

From: Slightly off center

Ion battery is in the trunk, no?
There are leads that run the length of the car to the front under hood area, so Andy's suggestion is still valid. My comment comes from the thought of a possible trunk leak

Nov 4, 2025 | 01:47 PM

derf

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Joined: Jul 2005

Posts: 12,315

From: Slightly off center

I think the battery sits in a vented compartment in the trunk. I suppose water could possibly splash up through the vent and cause problems with the battery.