Thrid break light not working. Where to look?
 

My stock 3rd brake light worked when I swapped it out to a spyder LED 3rd break light. The led worked for about 6 months till a month ago. I though what a piece of s***. So I put the stock 3rd break light on and it doesn't work. Next I did a voltage test on the stock truck wire that plugs in to the 3rd break light, and it has power.

I am very confused:sigh:

Anybody have a source containing the wiring diagram, google is not being reasonable with my search.

A lot of forms say it could be grounding some where, but would it still get power to the trucks connector for the light?

My third breaklight had oxidation on the brass/copper or what ever it is. Only half of my break light worked. I even replaced the bulbs. After I looked and looked for a reason I decided to take some fine sandpaper and try and clean it up a bit. I have a 99 so idk if its the same or not.

You may just have a blown fuse, or burnt out bulbs. I haven't seen these things with harness or grounding problems, but anything is possible. Here's the diagram you asked for. I blew it up so it's easier to see & read, so it's on two screenshots.

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Puuurrrrfect thank a lot guys. I look into the oxidation problem b/c origionly before my led light only one bulb lit up. I figured it was burnt out. When I took the led light off and installed the stock break light I put 4 new bulbs in it.

Do you think the led could have shorted something b/c the fuses look fine?

Ok so I only checked the fuse in the cab/dash that said brake. Apparently the 3rd brake light has a fuse labeled CHMSL.

The stock light works, but this leads me to the conclusion that my led 3rd brake light blew it......Now why, first I am going to call spyder led center and check to see if I have the correct bulb/housing for my year.

If the LED light is correct any suggestion on how to set it up to not blow the fuse? Maybe use the wiring diagram to design/allow for a larger fuse

The CHMSL fuse also feeds your trailer/camper wiring harness. So you may want to check those for short circuits/hacked wiring. The PO of your truck may have had a canopy, camper, or something else with a 3rd brake lamp. Scotch-Locks are your enemy, if you find any back there, get rid of them and fix the harness properly.

Just something else I've seen a ton of thoughout the years. :)

Have same issues ... The leds leak .. I could not find a leak that i thought i had in the cabin area after my truck got wrecked .. Turns out theres a thread a few weeks ago on here about aftermarket leds and all of them leaking ... My led third brake light went out a few weeks back when that thread came out on here and i took it off n it was full of moisture .. Put factory light back on and no water inside on floorboard or anywhere since BUT the factory third brake light still doesnt work .. Too busy working 6 nights a week to check .. Cargo light works fine though ..maybe we get this figured out

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I have a simular problem, but its my cargo lights that dont work. And the cargo light on the dash is on. What could this issue be?

I fixed a 99 Silverado today that was doing the same thing. PM me and include the year of your truck so I can look at a schematic. I'll get back to you this weekend. On the 99, it was a short circuit in the fog lamp bulb causing a backfeed.