brake light problem?

[Dav]

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?

 

[Uncle Gump]

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]

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]

I would vote trailer light wiring as well

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

 

[RobbieD]

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]

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

 

[Dav]

well, with all i have to do, fixing a ghost problem got put aside. until....
monday i got 2 miles from the house going to work. (different job site; 29.6 miles. 50 minutes in the morning, 2 hours in the evening tampa traffic). smelled burning plastic, thought it was someone else until i looked in the mirror. cloud of white smoke behind me. pulled into first driveway, smell less, no visible problem. drove 2 hundred yards and realized i had no instrument lights. U turn and back to the house. square box on the T connector for the trailer had oozed plastic out of it's guts. no tail lights. took the 88 to work (whole 'nother story there. curse walmart batteries)
last night found 2 blown fuses and removed the T. drove it to work today, no problem but when i got home i found i have no brake lights. can't find any more blown fuses and the owners manual does not list brake lights in the fuse section.
where is the brake light fuse? every thing else is working

 

[RonD]

Fuse 10 in cab is brake light fuse, 15amp

Does the 3rd brake light work?

 

[Dav]

fuse 10 is a 10 amp in mine. so i went to my 96 to get a fuse, that one has a 7.5 in slot 10. took a 15, put it slot 10, nothing. changed the switch on the pedal, nothing. ran a jumper wire from the switch and touched it to the battery, lights. so no power to the pedal. back to the beginning. checked all the fuses. number 13 was blown. judging from the undisturbed dust on it, i must have skipped that one when i checked the fuses the first time. everything is ok now.
thanks for the help.

 

[RonD]

Yes, in 1996 wiring fuse 13 is brake lights, fuse 10 is 7.5amp

So either my 1995 wiring diagram is wrong or you have a late 1995 Ranger with 1996 wiring