brake light problem?


Dav

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95 xlt 2.3 auto. has hitch and store bought plug in wiring connector for the trailer
in the mornings, when the truck has been sitting all night, i get in, put my foot on the brake and my instrument lights come on. so do the parking lights. the brake lights also work. when i get to work, 10 to 20 minutes later (4 miles, tampa traffic, 5 lights) only the brake lights work off the pedal. this has only been happening since the temps have gone below 50 at night.
any ideas on the cause?
 


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Uncle Gump

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Just a shot in the dark... but it sounds like a wonky dual filament bulb. I would try removing the tail lamp blubs one at a time to try an isolate the wonky blub.

The other thing that comes to mind is a bad ground causing the brake light circuit to find ground through the park lamps.

Of course none of this makes sense based on outside temp.
 

scotts90ranger

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I would look into that, I've had bulbs do odd things.

But also you are in Florida, it's damp and salty, I would unplug the trailer wiring adapter and check for corrosion, it could be a problem with that T connector.
 

RonD

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I would vote trailer light wiring as well

But "instrument lights" shouldn't be part of that, unless it just turn signal lights
 

RobbieD

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Parking lights could backfeed the instrument lights. All of the suggestions on what to check are right on- trailer harness, rear bulbs (and look closely at the two contacts in the bottom of each of the bulb sockets), and grounds.
 

Josh B

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Parking lights could backfeed the instrument lights. All of the suggestions on what to check are right on- trailer harness, rear bulbs (and look closely at the two contacts in the bottom of each of the bulb sockets), and grounds.
As the temps fall below 50 I suppose your humidity rises, pay special attention to Robbie's underlined statement as you search. I also suppose some corrosion could conduct best under higher humidity conditions.
I've known computer circuits all it took to connect was the scribe of a lead pencil
 
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