# 03 2500hd third brake light and brake controller issue



## dheavychevy38 (Nov 19, 2008)

The truck is a 03 2500hd with a 6.0 gasser in it. The problem is that the third brake light quit working and I also lost signal power going to my brake controller telling it that the brakes are being applied. Any ideas ? I have check what i thought is all the right fuses.


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## mcfly89 (Nov 2, 2005)

are the rest of your brake lights working?


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## dheavychevy38 (Nov 19, 2008)

Yep the ones in the tail lights work and from what I can tell the bulbs are good in the third brake light. Everything on the brake controller still works in other words if you use the manual over ride it works fine just has no power when you hit the pedal.


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## lilweeds (Aug 3, 2007)

Sounds like a bad brake pedal switch.


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## dheavychevy38 (Nov 19, 2008)

Is there a fuse for the third brake light ?


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## Bruce'sEx (Sep 16, 2006)

Did you use the pigtail for the brake control, that plugs in under the driverside dash? or are you hard wired?

if your hard wired find where your brake control is getting it's brakes on signal from, it almost sounds like it's tapped into the brake lights. Doubt it's a brake switch problem if the brake lights in the rear still work.


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## Bruce'sEx (Sep 16, 2006)

dheavychevy38;854986 said:


> Is there a fuse for the third brake light ?


likely same brake fuse for all the brake lights.


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## dheavychevy38 (Nov 19, 2008)

Fuses are all good and yes it is on the pigtail that plugs in by your left foot. I figured it wasn't a switch thing only cause the other lights still work fine.


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## wild bill (Feb 10, 2007)

*brakes*

sound's like 1 side of your controller is burned out ,if they work off the hand control and not the pedal .that's common on some low end brake control's .:salute:


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## dheavychevy38 (Nov 19, 2008)

I checked the wire comeing into the controller for power. The controller is a prodigy which my company uses in all of our trucks.


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## mycirus (Dec 6, 2008)

I have a 2001 GMC and have to use my manual control too for brakes on the camper. My third light works though. Here is what I found online about it. I havent tried it yet.

"Check the VEH CHMSL fuse on the side dash fuse panel. Activation comes from the third brake lamp. If that's good, then look to the harness.

The harness looks the same, but the plug's pin location changed on different model years. This may be where your problems lie, you may have the wrong harness.

The light blue wire is for the controller activation feed, and the brown wire is the controller illumination line (if equipped).

For orientation purposes, with the plug’s release tab at top, the early models had the brown at the top right corner and the light blue in the bottom left corner. Later models swapped these two pin locations."


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## mcfly89 (Nov 2, 2005)

also that harness has a separate fuse if i remember right


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## lilweeds (Aug 3, 2007)

No that fuse is only for the 12V charging pin in the 8 way trailer plug.


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## dheavychevy38 (Nov 19, 2008)

The truck has had the controller since the day it was bought in 03 and it has always worked up until now. I purchased the truck from the company that I work for so I know that it was in working order. As for the brake light that was working and just stoped within the last few days. I will defenitly check out that fuse on the side of the dash. Thanks guys and keep the ideas comeing.


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## dheavychevy38 (Nov 19, 2008)

Well just ran out to check the fuse that MYCIRUS said to try and dead on that was it fixed both problems. Thanks for everyones help. :waving: Thats one less thing to fix. :laughing:


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## mycirus (Dec 6, 2008)

Sweet, glad I could help.


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## mcwlandscaping (Sep 8, 2005)

Why did the fuse blow? Figuring that out may be a good idea...or at least giving all the wires and connections you can a real good look to check for any problems.


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## dheavychevy38 (Nov 19, 2008)

Haven't figured that part ot yet but im guessing something to do with the trailer I had hooked to it the other day. Still have to some digging as to why but when I figure it out I will post up.


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## mycirus (Dec 6, 2008)

I just went out and troubleshot mine and the wires were in the wrong pins. Put the brake wire on the bottom left instead of top right and it works like a champ now. Its about time I did this, I was using manual brakes all this time.


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