93 brake lights

Tiny
MIDNIGHTWOLF420
  • MEMBER
  • 1993 CHEVROLET SUBURBAN
I have a 93 suburban c2500 454 engine not that any of that matters. Anyways my lights were working a week ago I rented a trailer. Everything was fine. Then this week I went to rent another. When we hooked up the light harness everything works but the brake lights on my truck. Turn and operating lights work as well as hazards. I put in new bulbs on the running lights and reverse lights. They still didnt work. So I bought a the stop switch on the brake pedal itself. Still didnt do anything so I bought me a tester. I am getting the the stop switch seems to be working fine. The yellow wire goes on and off with the switch but I am not getting anything to the fuse box. Please tell me im missing something easy to check and replace. Thanks alot apperciate it
Friday, October 19th, 2007 AT 2:42 PM

11 Replies

Tiny
BLACKOP555
  • MECHANIC
  • 10,386 POSTS
Check for a pinched wire or one shorting out

it may not be recieving enough power to light up the bulbs. Test the voltage at the tail light that is out.
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Friday, October 19th, 2007 AT 2:56 PM
Tiny
MIDNIGHTWOLF420
  • MEMBER
  • 7 POSTS
I can do that but will it give me anything there if im not getting anything at the fuse the stop signal switch is working. But its hard to trace the wire cus I have added stereo system and a good alarm. Nothing at the fuse thats why I was wondering if there was anything between the switch and the fuse?
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Friday, October 19th, 2007 AT 3:01 PM
Tiny
BLACKOP555
  • MECHANIC
  • 10,386 POSTS
When you remove the harness for the trailer does your lights go back on?

Since you say theres nothing at the switch. Your talkign the one behind the brake pedal arm up at the pivot point?
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Friday, October 19th, 2007 AT 3:09 PM
Tiny
MIDNIGHTWOLF420
  • MEMBER
  • 7 POSTS
No only the brake lights dont work even when the harness isnt hooked up but has worked fine plenty in the past. The switch in the brake pedal itself works properly. So its something between that and the fuse. Is my guess but im a construction worker not a mechanic. I did notice that when I first found this problem I check all the tail lamps and there was a reverse light out. But not the other 2 lamps. I dont know if that would interfer. But I have replaced all the tail lamps since then. And yes sir it is the one up at the pivot I replaced it even though the old one seemed to be working
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Friday, October 19th, 2007 AT 3:18 PM
Tiny
MIDNIGHTWOLF420
  • MEMBER
  • 7 POSTS
I was just looking again and in the fuse box I got 1 that says brakes. Not getting anything with the switch on or off. Then theres another fuse called "stop" it has constant power to it with the switch on or off
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Friday, October 19th, 2007 AT 3:24 PM
Tiny
BLACKOP555
  • MECHANIC
  • 10,386 POSTS
Id take and bypass the switch momentarly. Id take the two wires going into the brake switch and touch them together. If the lights light then the switch is no good if it does not light id try a new wire harness for the brakes.
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Friday, October 19th, 2007 AT 3:30 PM
Tiny
MIDNIGHTWOLF420
  • MEMBER
  • 7 POSTS
I would loop it if I knew which wires to loop. Theres a orange one thats constantly hot and a yellow wire the goes hot when I presh on the brake pedal. Then theres about 4-6 more wires
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Friday, October 19th, 2007 AT 3:53 PM
Tiny
BLACKOP555
  • MECHANIC
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Since you say the one goes hot then the switch is good. Do you see a second switch under there? The best thing to do is take a wire from the one that goes hot when the pedal is pressed and follow it as far as you can

if it goes out towards the back take of the taillights find the wires and see if they have voltage if not you have a bad wire somewhere from the front of the truck to the back. Also look at the port that you hook the trailer too you could have a prong bent over in there touching another one shorting out the lights.
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Friday, October 19th, 2007 AT 4:04 PM
Tiny
MIDNIGHTWOLF420
  • MEMBER
  • 7 POSTS
Ok I traced the wire and it goes down into a brake control that ive never used it was on the truck when I had it. The control is for if I have a trailer with a brake system. The wire going into it is good but I cant detect anything going out.I dont see a splice in the wire anywhere so I guess I can only cut all the wire and try to bypass that?
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Friday, October 19th, 2007 AT 4:34 PM
Tiny
MIDNIGHTWOLF420
  • MEMBER
  • 7 POSTS
Ok blackop I figured it out man it was the alarm I had installed they just took off a piece of the rubber coat and taped the alarm into it. I dont know why it made my brakelights work but I re-spliced in the wires correctly using a connector and it all works now. Thanks again for yer help
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Friday, October 19th, 2007 AT 6:28 PM
Tiny
BLACKOP555
  • MECHANIC
  • 10,386 POSTS
Grats. I would have never thought a improperly installed alarm would make brake lights failure. What I was gonna have you do was go right from the swithc and ran it right to the brakes bypassing it thats what I would have had you done and htats what it seems you were thinking to.

But we learned a lesson on rigging things eh? Always do it properly
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Friday, October 19th, 2007 AT 8:25 PM

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