weird brake light issue - The 1947 - Present Chevrolet & GMC Truck Message Board Network

iamseth · 10-08-2011, 10:53 PM

My '72 C10 cheyenne was having some rear turn signal/brake light issues. The passenger side would not work one day, driver side the next, then BOTH sides went out. Magically the next morning they would all function fine and then by the time I made it to work.... one side was out again.

Turns out there was a cob web of wiring that was supposed to be a trailer hook up. Real nasty job. So, I pulled all that out and cleaned it up a bit. All the lights are working, but now this is happening:

When either turn signal is on, NO brake lights work.

Has anyone ever seen this before? After looking at the wiring diagram, it seems to me the brake/turn signal is fed by the same wire. I don't understand why the driver side rear brake light won't work when the passenger side turn signal is on and vise versa.

Thoughts?? Sorry for the long explanation.

highliner · 10-08-2011, 11:20 PM

I had a similar issue and i tore open my steering column and found a little plastic clip broken off of the turn signal cam that allowed the metal connections to travel to far, thus making the turn signal connection, but not the brake light connection. Really cheap part and easy fix. Try turning your turn signal on, then back it off slightly, and see if your brake lights come on. I hope that's your only problem.

highliner · 10-08-2011, 11:23 PM

Also, that turn signal switch in the steering column is what diverts power to the turn signals and brake lights. You can take off your steering column and it's right there for you to watch it all work. Hope this helps.

iamseth · 10-08-2011, 11:28 PM

Nice.

Will I have to pull column out completely?

Longhorn Man · 10-08-2011, 11:49 PM

nope, the column stays in place.
Odds are the switch needs replaced.

coop34 · 10-09-2011, 01:01 AM

Had the same thing happen to me. New turn signal switch took care of the problem.

iamseth · 10-09-2011, 02:12 PM

Thanks for all the input!

Highliner- I tried turning the switch about halfway (right before it clicks into place) and the brake lights didn't go off. Sounds like the switch.

So do I need to pull the steering wheel? I read in a couple other posts that you pull the shifter arm off, but thats all i could get from those. Sorry, I've never changed a TS switch before.

Thanks again!

10-08-2011, 10:53 PM	#1
iamseth Registered User Join Date: Jul 2010 Location: Austin, TX Posts: 29	weird brake light issue My '72 C10 cheyenne was having some rear turn signal/brake light issues. The passenger side would not work one day, driver side the next, then BOTH sides went out. Magically the next morning they would all function fine and then by the time I made it to work.... one side was out again. Turns out there was a cob web of wiring that was supposed to be a trailer hook up. Real nasty job. So, I pulled all that out and cleaned it up a bit. All the lights are working, but now this is happening: When either turn signal is on, NO brake lights work. Has anyone ever seen this before? After looking at the wiring diagram, it seems to me the brake/turn signal is fed by the same wire. I don't understand why the driver side rear brake light won't work when the passenger side turn signal is on and vise versa. Thoughts?? Sorry for the long explanation.

10-08-2011, 11:20 PM	#2
highliner Registered User Join Date: Feb 2009 Location: West Point, UT Posts: 29	Re: weird brake light issue I had a similar issue and i tore open my steering column and found a little plastic clip broken off of the turn signal cam that allowed the metal connections to travel to far, thus making the turn signal connection, but not the brake light connection. Really cheap part and easy fix. Try turning your turn signal on, then back it off slightly, and see if your brake lights come on. I hope that's your only problem. __________________ 72 C-10 Longbed (3rd generation truck) 79 K-15 Shortbed SBC400 4in. lift super swampers 05 2500HD Crew 6.0L 39 International P/U (future rat rod)

10-08-2011, 11:23 PM	#3
highliner Registered User Join Date: Feb 2009 Location: West Point, UT Posts: 29	Re: weird brake light issue Also, that turn signal switch in the steering column is what diverts power to the turn signals and brake lights. You can take off your steering column and it's right there for you to watch it all work. Hope this helps. __________________ 72 C-10 Longbed (3rd generation truck) 79 K-15 Shortbed SBC400 4in. lift super swampers 05 2500HD Crew 6.0L 39 International P/U (future rat rod)

10-08-2011, 11:28 PM	#4
iamseth Registered User Join Date: Jul 2010 Location: Austin, TX Posts: 29	Re: weird brake light issue Nice. Will I have to pull column out completely?

10-08-2011, 11:49 PM	#5
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: weird brake light issue nope, the column stays in place. Odds are the switch needs replaced.

10-09-2011, 01:01 AM	#6
coop34 Registered User Join Date: Sep 2009 Location: Visalia, CA Posts: 247	Re: weird brake light issue Had the same thing happen to me. New turn signal switch took care of the problem.

10-09-2011, 02:12 PM	#7
iamseth Registered User Join Date: Jul 2010 Location: Austin, TX Posts: 29	Re: weird brake light issue Thanks for all the input! Highliner- I tried turning the switch about halfway (right before it clicks into place) and the brake lights didn't go off. Sounds like the switch. So do I need to pull the steering wheel? I read in a couple other posts that you pull the shifter arm off, but thats all i could get from those. Sorry, I've never changed a TS switch before. Thanks again!

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