brake light problems

[Maverick]

My brake lights on my 2000 Chevy quit workin. My buddy tried running a ground wire from his boat trailer to my frame and this happened. The 3rd light still works. The turn signals, back up lights and hazards all still work fine. Check all the fuses and they are all fine.  Anyone got any idea what the heck happened and how to fix it? Thanks guys

[TONTO]

 Well if you have flashers and signals, it's not the bulbs, I would say it sounds like brake light switch, oh wait you said the third light works, does this work when the pedal is pressed.

[Rhinoron247]

You missed a fuse.  I have had the exact problem on my 02 and it was a fuse I over looked.

[timberghost72]

Fuse

And the wiring on the trailer sound like it is incorrect if it was plugged into the truck when you ran the ground wire to the truck frame. What kind of plug? Flat 4? Or he grounded the wrong wire.

[Maverick]

Where's the brake switch? I look over the fuses over and over and they're all fine. I even check ones that didnt have anything to do with my brakes.

[flinger]

change the bulbs

[timberghost72]

on your brake pedal above the foot pad. Probably has 3 or 4 wires on it. Did you check the under hood fuse box along with under the dash fuse box? Not gonna be the switch though.

[ICEMAN]

Did you check to see if your brake light element in both bulbs are toast? 

[high country]

Pull the wiring plugs that are behind the trailer plug and under the bumper, spray them out with contact cleaner. I have seen this before.

[flinger]

Did you check to see if your brake light element in both bulbs are toast? 

[farmin4u_98948]

You missed a fuse.  I have had the exact problem on my 02 and it was a fuse I over looked.

Did the same thing on my 01.   FUSE..

[Kowsrule30]

Same thing on my Dad's 03.... Fuse.... And a shotty ground.....

[timberghost72]

Did you check to see if your brake light element in both bulbs are toast? 

The OP said the turn and hazzard lights work ok. Assuming that they are not rapidly flashing or on steadily then the bulbs would be ok. The turn signal part of the bulb uses the same element as the brake light element.

[flinger]

Process of elimination
Check/replace bulbs
Check (with tester/Replace fuses
starting from sockets check all connectors with test light
If they blew when a wire was touched/Bulb or fuse
That is how they are designed

[lokidog]

Definitely check that under HOOD box.  Lots of little ones hiding in there.

BTW, if you ever get the 4WD to 2WD switches not working, be sure to check the underhood fuses as well.  Had a shop want to install a new switch so I did a google search and someone suggested a fuse under there, which was the case.

Good luck.