Headlight switch or controller

123ABC123

MEMBER
2010 MERCURY MARQUIS
195,000 MILES

Had a bit of rain come in my car threw a window while I was talking to someone. Got on the door and headlight switch. Now the digital speedometer and the display for heater only comes on when everything is supposed to be off.

Friday, December 14th, 2018 AT 9:06 PM

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,822 POSTS

Hello,

It sounds like the water shorted out either the door module or the headlight switch. Let try removing both and drying them out while checking the the connectors for corrosion as well. The headlight switch bezel pops off with the switch here are diagrams below to help you with the window switch. Use a hair dryer to get the water out of the switches.

Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.

Cheers, Ken

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Monday, December 17th, 2018 AT 11:08 AM

123ABC123

MEMBER
2 POSTS

The window switch is fully functional. Long with the power seat and mirror control.

The headlight switch is not functioning properly as the lights for just the digital speedometer and the heater display backlight are not functioning as they should.

I believe it may be the light controller instead of the switch.

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Monday, December 17th, 2018 AT 12:24 PM

KEN L

MASTER CERTIFIED MECHANIC
42,822 POSTS

Did you remove the switch to dry it out? Here is the headlight wiring diagrams so you can see how the system works and the location of the lighting module. I would remove the module to check for water damage as well. Check out the diagrams (below). Please let us know what happens.

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