97 c1500 brake lights out

[GreenVortec]

Brake lights are out, the third cab brake light works though, brake switch is new, the big 30 amp fuse under the hood blew last time the brake lights went out along with the small 20 amp fuse on the door panel, i replaced all those a month ago and now the problem is back, but all my fuses are intact and working properly.. what gives?

[ToyHauler]

did you take your housings out and see what you have at the plugs? ground could be out in the back. that would affect the rears only. also if the truck has a trailer plug sometimes those can cause issues, thats were i usually start if the truck has one

[GreenVortec]

did you take your housings out and see what you have at the plugs? ground could be out in the back. that would affect the rears only. also if the truck has a trailer plug sometimes those can cause issues, thats were i usually start if the truck has one

ill go check on this right now

[GreenVortec]

did you take your housings out and see what you have at the plugs? ground could be out in the back. that would affect the rears only. also if the truck has a trailer plug sometimes those can cause issues, thats were i usually start if the truck has one

nothing at the plugs.. dead zero. had a trailer harness, i unhooked it and hooked the brakes back up but nothing still. cleaned up the ground area with a dremel and wire brush and nothing either

[ToyHauler]

the switch and fuse must be good because the center one works, it says it goes through the directional. it must be after where ever they brake apart

[GreenVortec]

the switch and fuse must be good because the center one works, it says it goes through the directional. it must be after where ever they brake apart

where is the directional located exactly?

[HawgEnvy]

where is the directional located exactly?

Top diagram, top right corner

BTW, thanks for the diagram post. That will come in handy.

[GreenVortec]

More problems..

[ToyHauler]

i think all that goes through the directional so it can turn on the appropriate lights weather you have the fourways on or brakes or directional signals. thats what i would be focusing on. not real sure about the gas gauge or obd module. pretty sure those wiring diagrams are suspect as to its completeness after 96 especially. i dont have anything else though. i seem to remember some cars in that time period switching to an integrated flasher/directional module

[ToyHauler]

http://www.fullsizechevy.com/forum/g...rd-lights.html

seems like its all one unit

[GreenVortec]

so everything goes in through it? I've checked all the wiring underneath the truck, no tears or anything.
so my last bet is replacing this switch then..

[ToyHauler]

it seems expensive so i would check out everything i can first but, i dont know what else it could be. the thing that concerns me is the dash stuff and obd port. those have me thinking ground problem more than anything else. unless you have multiple issues. i would find the ground under the dash for that stuff and maybe make a temporary jumper strait to battery neg and see if that changes it

[HawgEnvy]

Try this. Pull neg batt cable and run a test light between the battery and the cable. Light=short. Start pulling fuses one at a time. Hopefully,you get the right one and the light will go out. Then trace the wiring for that circuit. Post back,don't leave us hangin'. Good luck

[GreenVortec]

Try this. Pull neg batt cable and run a test light between the battery and the cable. Light=short. Start pulling fuses one at a time. Hopefully,you get the right one and the light will go out. Then trace the wiring for that circuit. Post back,don't leave us hangin'. Good luck

i will definitely try this tomorrow morning. thank you for the info

[GreenVortec]

Try this. Pull neg batt cable and run a test light between the battery and the cable. Light=short. Start pulling fuses one at a time. Hopefully,you get the right one and the light will go out. Then trace the wiring for that circuit. Post back,don't leave us hangin'. Good luck

i just did this but the light on my test light never turned off, i did it for both the fuses under the hood and on the panel inside

[ToyHauler]

i think the idea is you pull every thing until you find it. but i would think you would have some normal stuff on like the radio, pcm, etc.

[GreenVortec]

i think the idea is you pull every thing until you find it. but i would think you would have some normal stuff on like the radio, pcm, etc.

I pulled AUX B and "lighting" on the underhood fuse box and my test light turned off.. Aux B only turns on if my LS harness is connected to it.. the wire that hooks on that post is for a relay for my LS harness.
Idk what lighting goes to

[ToyHauler]

i wish i had a good diagram for that truck, but you will have to work down that circuit and unplug stuff until you find it. whats a ls harness

[GreenVortec]

i wish i had a good diagram for that truck, but you will have to work down that circuit and unplug stuff until you find it. whats a ls harness

its the wiring harness for the LS motor in the truck. and yeah man im unplugging stuff like crazy right now

[HawgEnvy]

its the wiring harness for the LS motor in the truck. and yeah man im unplugging stuff like crazy right now

Did you do the install yourself? If there's any wiring you had to modify,check there first. I traded an old beat up Buick Regal for an '80 Chevy long bed w 6" lift and 35's because the guy had a constant battery drain and couldn't figure it out. The plug for the alternator broke and he clipped the wires and put spade connectors on it. He plugged them in backwards(noticed it when i looked at the truck). Towed it 2miles from his house,pulled over,switched the wires around and drove it home. PO was bummed about losing his fresh built 350. He was pissed when I told him what the problem was and that it was actually a fresh built 400ci.

Basically,start looking at the simple and inexpensive stuff first. Not sure what "Aux B/lighting" would be. I'd dig into the dash and unplug the harness from the headlight switch,dome switch,etc. maybe even your cig lighter socket. See if that checks out.

Just re-read. Replace that relay you talked about for the harness