Dash lights causing turn signal woes
 

In my '72 GMC I put in a completely new wiring harness from AAW- under dash, lights, and engine. New gauges, switches, etc. Also a new Ididit column.
The exterior turn signals work fine at all times.
On the dash, when the lights are off the turn signal indicators work as intended. When the lights are on and the dash lights are turned all the way off- everything is fine.
When the dash lights are turned up, all the lights including the turn signal bulbs are on, and then the turn signals flash opposite to the turning direction (signal left, right light blinks).
Ground issue? Short? Bad switch? All of the above?

Thanks!

Re: Dash lights causing turn signal woes
 

Run a ground between the small screw above the speedo and the cab.

Re: Dash lights causing turn signal woes
 

Thanks, I have one on the bottom screw to the cab. I may have a bad tail light socket as well.

Re: Dash lights causing turn signal woes
 

I have one too, but it has 0 effect on my dash.

Re: Dash lights causing turn signal woes
 

I found this old thread and I am having the exact same problem with my 68. Any thoughts? All of my outside lights are working correctly.

Re: Dash lights causing turn signal woes
 

I checked the ground and ran one to the back of the cluster with no change.

Re: Dash lights causing turn signal woes
 

I answered you in PM. If you find out what it was post the result in here for all of us to know. Thanks.

here is what I answered.


I saw the thread but just haven't had time to reply. I did some thinking on it and I believe you have a turn signal light, front or rear socket to ground that is poor and it gets enough ground to work when the headlights and dash lights are off but when all is on then whichever socket has the bad ground will use the easiest path to ground and that may be one of the turn signal indicator lights in the dash. I would suspect the headlight ground to the core support as well as a socket. You might try unplugging each of the headlights one at a time and watch for the TS indicator lights to go out. If they do it tells you which light has the bad ground.
You can do the same thing with the park turn lights and the tail turn lights until the indicator lights go out

Look for any light that is dimmer than it should be when the turn signal is off and that should be the bad grounded one.

You 68 doesn't have marker lights so that is two that you don't have to worry about.
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Re: Dash lights causing turn signal woes
 

Thanks again VetteVet. It will be a couple of days but it will be done.
Rick

Re: Dash lights causing turn signal woes
 

Well I put the lights on the back burner while I got the factory a/c working. Tonight I cleaned the grounds and the sockets with no success. I even went so far as to run a long ground wire to each of the lights directly from the battery and wedge the bare wire between the bulb and socket with no difference. I cleaned the two plug in's going to the steering column. I did notice when I would remove the front driver side parking / turn signal bulb or un plug it my dash lights would go out. Even my high beam indicator light comes on when I turn on the parking lights. But when I turn on the light it will shut off on low beams. All the fuse's are hot in the fuse box. Any other thoughts?

Re: Dash lights causing turn signal woes
 

I did not think it was the headlight switch but I replaced it today anyway. No luck still the same thing. Lights off all is good. Parking lights or headlights on with the dash lights turned up turn signals glow and work backwards. Dash light dimmer turned off all works as should. I do have 2 factory wires off at the fuse box. A 16-18 ga pink and a larger red one. They don't seem to do anything when hooked up.

Re: Dash lights causing turn signal woes
 

There's the clue.. That light has a bad ground.. The socket is crimped to the light housing and the housing is bolted to the bumper. both those contact surfaces are ground paths.. Remove the entire light assembly and check it thoroughly.. The socket crimp is probably where the ground is bad.. I have a 400 watt soldering iron. I had a grounding problem with a crimped socket so I cleaned the corrosion and paint off the exterior surface and flowed a "solder bridge" between the socket and housing.. No need to solder all the way around, one little spot is all that's needed. The light still works perfectly today..

When you re-install the light housing, clean the contact surfaces on the light housing and the bumper.. Smear a small amount of grease on these 2 surfaces and the corrosion won't return..

Re: Dash lights causing turn signal woes
 

Well here is what I did today. Re-checked all my bulbs and connections. Scotch bright the bulb bases and re cleaned all sockets. Re assembled using dielectric grease. removed the front parking lights and reassembled making sure grounds were good. License plate lights were not working wiggled them around and they came on so I figured this may be it. I removed them soda blasted inside and out cleaned up re painted and re installed. They work great now but did not help the lights inside. Re cleaned the dash bulbs and checked each socket individually all ok but no luck. Ran a alligator clip from the one ground screw on the passenger side nothing. Did the same thing on the driver side ground and nothing. I was looking over a old printed circuit and noticed the turn signal lights and 3 of the 4 dash lights ran off of the same ground going through the printed board. Used my test light and noticed it would light up on both sides of the bulb NO GROUND. Tightened up that ground screw a little more and BAM all got bright and no turn signal glow!!! I had even ran a test ground to that screw but it did not go through the printed circuit.
Sorry this is so long but I know this subject has been brought up several times and wanted to be specific on what all I did before I found the culprit.
I want to thank everyone who gave me some excellent advice on this pain in the ass issue.

Rick

Re: Dash lights causing turn signal woes
 

Hey Rick, my truck has intermittently had the exact same issue as yours over the last few years... tonight it happened and I couldn't get it to stop by turning the lights on/off as I have in the past. So, very glad to see this recent post. Can you clarify what ground screw you found to be the culprit? Is this on the printed circuit in the dash? And, if so, can I access this screw without disassembling the dash? Thanks!

Re: Dash lights causing turn signal woes
 

You can access it from behind the dash there are two quarter inch screws just loosen them up a bit and then retighten them being careful not to tear the printed circuit

Re: Dash lights causing turn signal woes
 

Thanks, I'll try that!

Re: Dash lights causing turn signal woes
 

I just started experiencing this same issue in my 72 c10. I think this all goes back to when I pulled the gauge cluster to repaint the needles and clean up the lens. I remember putting the thing back together some what cautiously because I didnt want to over tighten those little screws and crack or rip the printed circuit board. So I'll get back under there and give em a lil more torque. I'm so glad I found this thread before I called my electrician buddy.:)

Re: Dash lights causing turn signal woes
 

This is the perfect cure for dashboard CAT EYES . Tighten the upper GROUND 1/4 “ screws Left and Right of the T/ S lights . No more Headlights high beam issues or Turn Signals lit. (CAT EYES). Thank you Kindly

Re: Dash lights causing turn signal woes
 

Had a similar situation after installing my rebuilt gauge cluster, I ran a ground wire from the gas gauge to the tack and then on down to the 1/4 screw between the amp & temp gauge and from there to a ground screw on the emergency brake on my 69. Everything seems to be bright and tight now.