Tail lights problem
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7th Gear
Joined: Oct 2025
Posts: 7
Likes: 3
Tail lights problem
Hey guys new to this forum. I have an electrical issue I need help with. My rear tail lights turn on as soon as the ignition is on. All directionals work as well as Amber's and headlights. My problem is I dont have brake lights. I've changed the hazard flasher and the headlight switch as well as the brake light switch.
Fleet Mechanic
Joined: Aug 2007
Posts: 1,834
Likes: 260
From: Piney Woods of East Texas
Have you checked the brake switch on the petal under the dash? These are normally closed. When at rest the button is pressed keeping the lights off. A easy test is to unplug the wires to the switch and short together, brake lights should come on.
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7th Gear
Joined: Oct 2025
Posts: 7
Likes: 3
I've changed it
Laughing Gas
Joined: Apr 2024
Posts: 805
Likes: 262
From: Laramie Wyoming
Couple things.
Are the bulbs good for your tail lights?
Secondly, I had this happen on my 68 and I had to run a complete new harness from the plug at the firewall back to the tail light harness.
It started with one brake light not working and then went into both not working as well as flashers.
you might want to check the harness.
Are the bulbs good for your tail lights?
Secondly, I had this happen on my 68 and I had to run a complete new harness from the plug at the firewall back to the tail light harness.
It started with one brake light not working and then went into both not working as well as flashers.
you might want to check the harness.
Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
Agree. If the truck has dual exhaust, or a trailer hitch, or has had any other work going on, look for melted and shorted wires in the harness along the frame.
Check the bulb sockets to make sure nothing has crossed over, but that wouldn’t explain the power with the key.
The melted harness could, or any basic short circuit.
You’re gonna have to do a lot of inspection to find out why the power is coming on with the key, even though you’ve replaced switches.
And hopefully you have not thrown away the old switches, because they may be perfectly good. Not only that, but they may be better than the ones you bought.
In spite of their age.
Check the bulb sockets to make sure nothing has crossed over, but that wouldn’t explain the power with the key.
The melted harness could, or any basic short circuit.
You’re gonna have to do a lot of inspection to find out why the power is coming on with the key, even though you’ve replaced switches.
And hopefully you have not thrown away the old switches, because they may be perfectly good. Not only that, but they may be better than the ones you bought.
In spite of their age.
Thread Starter
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7th Gear
Joined: Oct 2025
Posts: 7
Likes: 3
Agree. If the truck has dual exhaust, or a trailer hitch, or has had any other work going on, look for melted and shorted wires in the harness along the frame.
Check the bulb sockets to make sure nothing has crossed over, but that wouldn’t explain the power with the key.
The melted harness could, or any basic short circuit.
You’re gonna have to do a lot of inspection to find out why the power is coming on with the key, even though you’ve replaced switches.
And hopefully you have not thrown away the old switches, because they may be perfectly good. Not only that, but they may be better than the ones you bought.
In spite of their age.
Check the bulb sockets to make sure nothing has crossed over, but that wouldn’t explain the power with the key.
The melted harness could, or any basic short circuit.
You’re gonna have to do a lot of inspection to find out why the power is coming on with the key, even though you’ve replaced switches.
And hopefully you have not thrown away the old switches, because they may be perfectly good. Not only that, but they may be better than the ones you bought.
In spite of their age.
Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
Haha! Yeah, that would certainly mess with things.
I hope that turns out to be the one and only issue.
I hear the “switch fell apart in my hands” comments more and more these days. Especially with the fifty year old versions.
I hope that turns out to be the one and only issue.
I hear the “switch fell apart in my hands” comments more and more these days. Especially with the fifty year old versions.
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5th Wheeling
Joined: Jun 2025
Posts: 43
Likes: 13
The headlight harness plug on my 1968 is being held together by hopes and prayers, and there's not enough wire to replace/splice in a new plug. These plastic parts have worked for way longer than the engineers who designed them could have ever hoped for!
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Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
I hear that. They’ve been pretty amazing to be honest. New stuff is crap by comparison. When I got my 71 back in 76, the dual tank selector switch was pretty buggered up, but back then I could get a new one right from the dealer still. Everything else lasted a long time
Even my headlight switch is still original. After it started tripping the breaker one night, I changed to a relay setup for the headlights, and the original switch kept on chugging away and is still in there.
Even my headlight switch is still original. After it started tripping the breaker one night, I changed to a relay setup for the headlights, and the original switch kept on chugging away and is still in there.
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