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Discussion Starter #1
My friend just came over and his 2000 Blazer's tail lamps and turn signals are working fine but the brake lights don't work; however, the 3rd brake light lights up as it should. The fuse under the hood is intact. Any clue what the problem is?
 

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The Blue Pwns Joo!
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Did you try testing or swapping the fuse out anyway? I've had fuses go out and look completely fine, like the contact broke inside the fuse 'housing'. Usually happens with constant on/off fuses, like tail/brake lights.
 

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Discussion Starter #3
yeah I've had that problem before too and no I haven't tried it. If the fuse is blown though shouldn't the 3rd brake light be out too?
 

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The Blue Pwns Joo!
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I'm not 100% sure on Blazers, but I know my S10 has a seperate fuse for the 3rd brake light and I would assume its the same on both... the lower brake lights probably have their own fuse becasue they're on a seperate circuit.
 

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Discussion Starter #5
I'll check it out but I thought the same thing but I couldn't find a separate fuse listed. We were working in the dark though so I'll look tomorrow. Thanks man.
 

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The Blue Pwns Joo!
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Should be the second one up from the very bottom right on the diagram (or the top right if you're looking at the box facing the rear of the truck).

Hope that works for ya!
 

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The Blue Pwns Joo!
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Gotcha.

Another thought... does the truck have a trailer light harness? If so it'd be worth checking our that connector if the fuse isn't the problem. Even if its factory there a chance it could've come loose or be corroded.

It took me about 4 hours to figure out that was the problem when the right brake light on my Dad's Colorado stopped working, lol
 

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The Blue Pwns Joo!
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Good luck!

Subscribed, lemme know what happens!
 

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i saw what you did there!
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i swore that i replied in this thread but apparently not hmmm


well if its not a fuse or relay then its 100% sure the sig switch assembly in the column

this is the first thign i check when someone has third light but no loer lights
and its always been fried sign switch assby
 

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Discussion Starter #14
Where's the relay located at?

well if its not a fuse or relay then its 100% sure the sig switch assembly in the column

this is the first thign i check when someone has third light but no loer lights
and its always been fried sign switch assby
Are you talking about the multifunction switch with all wiper controls and cruise?
 

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Electrical Mod
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The multifunction switch is common to go bad and will cause that issue.

But before doing that. Do the Hazards work and is the switch fully intact?
 

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Discussion Starter #16
I'll have to ask him next time I see him. I've been working on my Blazers non stop and my wonderful friends have quit talking to me during this time lol
 

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Electrical Mod
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If the tail lights work with turn signals then is has to be the multifunction switch. The circuit litterally goes from the brake switch straight to the multifunction switch. Only other thing would be a bad wire or connection from the brake switch, but that's unlikely. From the multifunction switch the turn/brake signal goes through a fuse and then to the left/right turn/brake light, they are on separate fuses of course. So if the turns work the only thing that bad is from the brake switch to multi. So you're really only left with one faulty switch, and it isn't common for them to go bad.

Somewhere there was a thread where a guy disassembled one and cleaned it up, removed a bunch of grease that was in the wrong places and was able to get it working.
 
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