Chevelles.com banner

1 - 18 of 18 Posts

·
Registered
Joined
·
45 Posts
Discussion Starter #1
Argh!!! Very confused, just installed a new turn signal switch under the impression it would fix my problem, (I thought this because a certain parts store told me it was probably my problem). Anyways my problem is that when I use my turn signals my hazards come on, either way, and when I use my brake pedal, niether the hazards nor the signals come one. I just replaced the seitch and... Same problem, Please Help me!
 

·
Registered
Joined
·
1,883 Posts
It would be helpful if you could provide a few more details about your problem.

How and when did it occur? (i.e. One day it was good - next day it was bad)

Has their been work on the vehicle wiring? Was the vehicle wiring harness replaced?

Do you have power to the brake light switch? The Orange wire to the switch should always have full voltage regardless of the ignition switch position.

When the plunger on the brake light switch is out (brakes applied) you should have continuity through the switch.

When the brake pedal is applied you should have full voltage at the White wire that is at the very end of the connector leading into the steering column switch.

There are two filaments in your tail light bulbs. The hazard and brake light filaments in your rear bulbs are the same. The turn signal and tail light filaments are the same.

I have a 1971 Chevrolet Shop Manual. It says for the Chevelle Wagon the right hand tail lamp will have a Dark Green wire for right turns. The left tail lamp will have a Yellow wire for left turns.

Hopefully, these facts may help you identify your problem.

JIML82
 

·
Gold Founding Member
Joined
·
63,044 Posts
Originally posted by JIML82:
The hazard and brake light filaments in your rear bulbs are the same. The turn signal and tail light filaments are the same.
Don't you mean the hazard, turn signal and brake light filaments are the same filaments and tail light filaments are seperate?
 

·
Registered
Joined
·
45 Posts
Discussion Starter #4
Sorry I didnt furthur explain, Yes it just kind of happend, there has not been any work on the wiring and I have not replaced the harness, and thanks for the facts I will check those out, any more help would be appreciated as well
 

·
Premium Member
Joined
·
2,173 Posts
"Anyways my problem is that when I use my turn signals my hazards come on, either way, and when I use my brake pedal, niether the hazards nor the signals come one."

But do the brake lights come on when you step on the pedal??

I'm also assuming we're talking about a 71 Wagon. Is this right? The turn signal and emergency flasher circuit use the brake light circuit. They actually interupt power to a brake light filament to indicate a turn. Conversely, they energize the brake light circuit if your foot isn't on the pedal. So your problem is most likely in the part of the circuit related to both the brake switch, the turn signal and the flashers (don't remember if there are one or two in that year).

I'm assuming all that sound equipment install didn't mess with any of the wiring. That you actually used the original radio feed and one directly from the fuse panel.

I'm assuming you have already replaced the flashers with good units, the new turn signal switch is the correct one, and the bulbs are good in all the lights. They aren't that expensive. Replace all 4. Plus, it gives you the opportunity to make sure no corrosion is going on in the sockets. Spray the inside of each socket with CRC556 or even WD 40 and install the new bulbs. They aren't the best but they are better than corrosion.

Next, take a flash or drop light and closely examine all the under dash wiring in the area of the steering column (especially inside the steering column), fuse panel, and brake light switch. Make sure nothing is rubbing or has been pinched. Look for a bad switch or connetion in the column or damage to the harness leading to that area.

The only other thing I can think of right off hand that causes cross-feeding like that is grounding problems. Yeah, I said grounds. I once had a brake/turn signal problem because it was back feeding to ground thru a parking light filament. THAT was a bear to find. that's why I said to replace all bulbs and clean all sockets and ground connections. It's a cheap easy way to eliminate problems in those areas.

If you don't find your problem after trying these things (maybe you already have) I'd say it's time for some expert local help who can read a wiring diagram and use a volt and ohm meter. (If that's not you)

Keep us posted and we'll keep trying to help.
 

·
Registered
Joined
·
1,883 Posts
I am quite sure you are right. The turn signals, hazard, and brake lights are the same filament. The running lights are a second filament.

I went out just to check the rear filaments in my 1975 Vette and guess what? I don't have any brake lights!!!

Looks like I am in for a day of fun. You should try and crawl around under a Corvette dash!
 

·
Registered
Joined
·
45 Posts
Discussion Starter #7
Thanks alot for your help everyone, especially you, Herb, I am going to check today, and yes, my brake lights do work. Thanks!
 

·
Gold Founding Member
Joined
·
63,044 Posts
Originally posted by JIML82:

I went out just to check the rear filaments in my 1975 Vette and guess what? I don't have any brake lights!!!

That's funny Jim, if you need any help be sure and ask back here.

:D

How do they ground the tail lights on a glass body anyway?
Guess that's a stupid question isn't it?
 

·
Premium Member
Joined
·
2,173 Posts
Jim,

Isn't it easier to hold the Vette upside down over your head than try to crawl under one of those dashes? :D

Cky12K, I THINK (not sure) your brake light switch is downstream from the flashers and turn signal switch. Or, it's at least in parallel with them. That would mean the problem is upstream from that switch, i.e. turn signal sw. or wiring, or flashers. Again, if the harness or wiring has been damaged or hacked, that's a good place to start.

Good luck and let us know what you find so everyone can benefit from yor experience. that's what this group is all about.
 

·
Registered
Joined
·
1,883 Posts
Last year my brake lights didn't work. Every once in a while, they would work ONCE then nothing! After much searching I found a capacitor wired across the brake light switch. Bubba had wired it sometime before I bought the car 18 years ago. I figured that the capacitor went bad with time. I removed it and my brake lights seemed to work correctly.

Now I seem to have the same problem again. (But there is NO capacitor in the circuit.)

I have turn signals, hazard flashers, and running lights. Just very intermittant brake lights.

I checked the orange wires to the brake light switch - 12 volts. I checked continuity of the switch itself - seems to function correctly. So now I am led to the Saginaw steering column. BTW, a NOS T&T turn signal switch is a VERY difficult part to find.

A plastic bodied car has to have separate ground wires from each light socket that goes to a metal ground.
 

·
Premium Member
Joined
·
2,173 Posts
Jim,

That capacitor install is a carry-over from an electronics engineering practice to reduce contact burn in switch circuits. Not normally done in simple DC auto circuits.

YOu may in fact have an intermittant brake light switch or ground. I'd check that before messing with the turn signal switch nightmare. When the brake lights DON't work, unplug the brake light switch connector and short the two connector contacts together with a clip lead or even a paper clip. This essentially elimnates the switch. That should cause the brake lights come on and stay on. If they don't, you do have other problems.

YOu may then want to run a home-run ground from the negative sideof the battery to the brake light ground lead to see if that make them come on. If so, you know what you need to do to the ground side of the brake light circuit. Use a long piece of #12 or 14 primary stranded wire and a big clip on the battery end and small alligator clip on the other. Keep this wire as it is invaluable for trouble shooting ground probs.
 

·
Registered
Joined
·
1,883 Posts
I feel kind of bad for hijacking this post. However, I don't think that people would look too kindly at a Corvette problem on the Chevelle board. So here is one more reply:

Herb,
Looking at the Vette electrical schematic, I should be able to disconnect the body harness from the steering column turn signal switch. Then I should be able to jumper the White wire coming from the brake light switch directly to the Dark Green and the Yellow wires going to the rear lights. If they go on when I depress the brake pedal, the problem should be in the column itself.

Although your thought on a jumper wire all the way to the rear lights is a good one. With the plastic body, Vettes are notorious for ground problems.
 

·
Premium Member
Joined
·
2,173 Posts
Jim,

Understand about the Corvette problem thing but I think people benefit from these kinds of discussions. I think Dean agrees and that's why he invited this discussion.

BTW - CKY, what's happening with your problem???

Isolating an electrical problem can be a challenge. Jim, you sound like you can read a wiring diagram so that helps. Isolating a ground problem is hard for anyone, even electrical engineers :D . So I wouldn't worry too much about the car type. The practice of isolating the problem is the same.

The long lead to the negative post of the battery that we call a "home run" ground is a common paractice to insure a soid ground then testing. If you hook a test light to this ground andprobe a ground lead (or side of a socket) and the light glows dimly, the ground (lead) is "floating" I.E. not solidly grounded. This works with any vehicle. I use a digital volt meter. If there is voltage on the ground lead, it's floating. Older fibergalss body vehicles are famous for ground problems as are older Chevelles and others. The ground connections get rusty or, with the advent of POR 15 and other coatings, the grounds are not metal to metal solid connections. This a comon problem when we try to protect the frames from weather and rust with thick excellent coatings.

FYI - on many newer vehicles with computers, the frame and body is not grounded to the battery!! Toyota trucks are famous for this. A home run ground is required to install trailer hitches with electric brakes for example.

Goodluck finding the floating ground. If I can help let me know.
 

·
Registered
Joined
·
45 Posts
Discussion Starter #14
Still havent figured it out yet guys, I have been pretty busy with work, I will keep you guys updated when I find it though! Thanks! Oh, and one question, If I have other things running through my fuse box, could that be causing the problem, I just recently hooked up my overdrive and tach, and I am going to go inspect where I plugged it in at. Thanks guys
 

·
Premium Member
Joined
·
2,173 Posts
cky12k,
Those things shouldn't cause the problem, but disconnect each one of them just to see if the problem changes. (I'm betting it won't). Pay special attention to the flashers and hazard light switch/wiring.

This is the second 71-72 Chevelle currently with the problem of hazard/turn signal circuit being constantly activated by something. What is different with the wiring in these years?
 

·
wagons rule!
Joined
·
3,247 Posts
sounds like a ground problem. sometimes the springy contact in the light bulb sockets are either corroded or need to be pulled back out to make good contact with the loght bulb. if not that sometimes the wire is broke inside the bulb connector where you cant see it easily.
 

·
Registered
Joined
·
45 Posts
Discussion Starter #17
Ok, so I finally got it!! Thanks for your help everyone, but it ended up being something totally unexpected, it was 4 Red wires intertwined, pushed up in my rear bumper, I am guessing it was set up for towing a trailer with lights, and when I uncrossed the wires, all was good! :D Thanks again for your help everyone.
 
1 - 18 of 18 Posts
Top