Thread: Wiring sucks!

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As you figured out from the title I have been having some trouble with my wiring. It's only 36 yrs old so why should it give me any trouble?
Anyway, my brake lights work and my turn signals work but they won't at the same time. My brake lights will be on until I hit the turn signal then they BOTH go off, not just the side the turn signal comes on. As soon as I turn off the turn signal the brake lights are just fine. Headlights on or off I get the same thing. Tail lights stay on like they should as do front park lights in bumper.
Any ideas where to look at to start with? Headlight switch is only 1 1/2 yrs. old and my domelight has stopped working also and the bulb is still good with new wire harness for it last summer. Not an expert at anything but I really suck at wiring! Thanks for any ideas of which way to attack this from.
Sorry, forgot to add, this is a "71" chevy 1/2 ton, 2 wd pickup with no air and no comps or any fancy electronics.

Unless somebody changed it,the power comes out of the brake light switch,up the column,and out through the turn signal switch to the taillights. Sounds like that's where your problem is. Hank

Like Hank mentioned that stuff goes through the steering column. That's how it knows to have the brake light on solid (braking) or on and flashing (braking and turning).

I'd also look to make sure the bulb sockets are clean, grounded, and the wiring is in good condition.

As for the dome light, isn't there a separate fuse for that? My experience with the newer (offshore made) headlight switches, quality wise, isn't that great. I've had some right out of the box that have dead spots for my gauge light dimming. The dome light is just a switch position when you turn the knob all the way CCW. So the dome light problem has to be the switch, fuse, bulb, or wire. Once again, you might want to check the socket, and wiring. If I recall correctly the dome light has 12 volts constant and the ground is supplied through the door switches (when open) or the headlight switch. If that ground connection is bad you'll loose your dome light.

I'd check the simple things first.

Make sure the lights have a good ground. There should be a ground wire somewhere (either off the battery terminal or from the engine to the body). Many trucks also have a small ground wire from bed to the cab or body... make sure it's connected. You can run a temp ground wire from the frame ground wire on the lights to do a quick check. .

Next would be the plug on the wiring harness that comes out of the steering column. Besides the plug being tight make sure none of the individual wires have backed out of the plug.

If the problem is not there I suspect yo will find you have a bad turnsignal switch.

Yep, grounds are probably the single biggest source of problems in an electrical system. You may have just enough ground when trying one light, but when you try to add another into the circuit it is too much.

Make sure all the sockets and grounds are super clean and check them out with a test light or Volt ohm meter.


Don

You can get a new prewired 12 or 21 circuit universal harness off of Ebay for just a little over $100.00. At that price, it's just not worth messing around with the old stuff. Save yourself a lot of future headaches.

If you send me a PM I'll try to help you with your problem this weekend 9/21-9/23.

Thanks for all the input, everybody. I guess I'll start checking out the grounds and bulb sockets and work my way up from there. Haven't had much time to fight with this stuff, starting early and working late. Even got scheduled to work this weekend, of course! Guess it's time to drag out the hand lights and go at it in the dark-that's where I started at, anyway.
Thanks again for all the input and pointers to work with. Good stuff.

Although bad grounds are the source of many electrical problems and especially in a pick up truck I believe your problem could very well be in the turn signal cam located in the steering column.

Okay, now that you mention that I recall having to lightly buff the contacts on that to get a signal to work again. Didn't grind hard on it but went over it real light with fine wet/dry paper. Probably should change it out just to eliminate that as a source of trouble. Thanks for the brain "jumpstart"

Originally Posted by burrbrian

Okay, now that you mention that I recall having to lightly buff the contacts on that to get a signal to work again. Didn't grind hard on it but went over it real light with fine wet/dry paper. Probably should change it out just to eliminate that as a source of trouble. Thanks for the brain "jumpstart"

My offer to help still stands.

NTFDAY, your offer is much appreciatted, I'm off to work this morning and will see how long I get tied up for today and find out if sunday is going to get taken away from me after I get there. If I'm free for sunday I'll PM you and see what we can work out. It's cool to have people like you around that love cars and digging into them. Will holler later about any free time. Off to make a penny or two.

Well, better late than never. Finally got some weekend time off and dug into steering column and found a MAJOR disaster area with the turn signal switch setup. The whole unit looked as if it had a meltdown at some time or other with all the little brass looking contacts as victims. After seeing what had and didn't have juice going in and out of them I bit the bullet and replaced the whole switch set-up and to my surprise it all works as it should now. If I can get my back-up lights lined out now all my lights will be operational as origonally designed. Thanks again for all advice and input and sorry so late with update.

What's kind of tranny in your truck?

The reason I ask is that will determine where the back-up light switch is located.