Turn Signal Problems
 

I'm having some weird problems with the turn signals on my 72 Custom deluxe. When the headlights are ON the front park lights won't flash with the turn signals at all but the side marker lights will flash. When the headlights are OFF all the front turn signals work fine, same story for both sides. Also the rear side marker lights won't flash with the turn signals at all, with or without the headlights being on. I noticed to that the signals flash faster when the headlights are OFF and slower when they are ON. This has got me stumped! I have spent about 4 hours so far checking bulbs, sockets, wiring, grounds, etc. etc.. I'm not coming up with much, wondering if maybe anyone could point me in the right direction? Thanks guys. Joseph

Re: Turn Singnal Problems
 

looks like a ground issue with either the headlights or side marker lights

Re: Turn Singnal Problems
 

The rear side markers never flash. The fronts it sounds like you may have the bulbs in wrong or wired up wrong, meaning the low filiments are flashing and the high filiments are on with the headlights. If that's the case they would appear to not flash with the headlights on because the highs are over powering the lows, if that makes sense.

Also could be a bad ground at the front bumper, you could try taking a wire and holding it on the bumper and the other end at a good ground or the negative battery cable and see if your problem goes away.

Re: Turn Signal Problems
 

Grab a Multimeter (VOM) and start checking the sockets, wires and grounds.

Re: Turn Singnal Problems
 

Thanks for the help guys. Thats good to know about the rear markers, i won't worry about them anymore. Now on to the front park lights, i don't see how the bulbs could be in wrong, they only fit in the socket one way? I think the ground is ok or else they wouldn't work at all and the turn signals work fine with the headlights off. With the headlights on you can see the low filaments barely flashing but the high filaments are brighter. I think this is exactly my problem! How would i go about rewiring them to correct this problem? The wiring looks original and untouched, doesn't make any sense to me! Thanks guys. Joseph

Re: Turn Signal Problems
 

Just ground them one at a time and see if it changes the problem. If it does then you know which one has the bad ground.
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Re: Turn Signal Problems
 

You are correct in thinking that they are supposed to only go in one way, but they can be forced to go in the other way, seen it many times. Take the bulbs out and look at the little tabs on the bulb and the slots they go into in the socket and make sure to line them up. The tabs are really easy to bend in so if yours have been put in wrong they are probably bent in and will easily go in either way.

Re: Turn Signal Problems
 

I am fairly certain this is a ground issue

Re: Turn Singnal Problems
 

I was just going by what he said about the lows blinking and the highs being on steady, should be the other way around.

Re: Turn Signal Problems
 

I will look at the grounds again and also the sockets, i could have overlooked something. Hopefully it will be a little warmer out in the garage tomorrow so i will try and check it out some more. Thanks for all the help guys. Joseph

Re: Turn Signal Problems
 

check all grounds. I went through the problem with the rear lights, reverse lights and side markers. cleaned all braided ground wires and added another to the rear box and frame and the lights work great.
One thing I would check are your front blinker lights, make sure they are secured to bumper and sockets are tight.

Re: Turn Signal Problems
 

Good thoughts. Sometimes the brass bulb sockets will be loose in the park light housings, causing a bad ground. I have used a small punch and hammer to tighten these up before without removing them from the truck. Joseph

Re: Turn Signal Problems
 

How does this work? not sure how your would use a punch to tighten

pic? diagram?

Re: Turn Signal Problems
 

Solid

Re: Turn Signal Problems
 

Ok...doing the ground test....the wiring diagram shows a ground coming from the parking light assembly.

What’s that? It’s not part of the harness that I can tell from the diagram or other pics on the forum.

Is it “just grounded” because it’s attached and front core is grounded?

Re: Turn Signal Problems
 

You might want to check the charging system with an ammeter or one of those toasters you can get at napa, just to make sure your alternator is putting out enough juice. Weird things can happen when you don't have enough voltage and/or amperage.

Re: Turn Signal Problems
 

Oh jeez, just realized how old this thread is.

Re: Turn Signal Problems
 

Yeah ....the search feature is great...sometimes you can find really old stuff....

That said...any suggestions where the ground for parking light comes from?

Re: Turn Signal Problems
 

Yes, the ground should be the housing for the light socket, same as GMC. I've had the marker lights go out before and I just spin the socket back and forth in place and they come back on.

Re: Turn Signal Problems
 

Ok...but where does the socket get it’s ground from? Is the socket itself grounded? I don’t see that wire coming out of the pigtail...and I don’t see a ground wire in the wiring harness (3 wires...but none are ground).

All of this leads me to believe the housing itself is grounded somehow. The wiring diagrams from the forum even show ground from the light itself. Just not sure how it gets the ground

Re: Turn Signal Problems
 

Yup, the light housing is the ground. Housing, bumper, frame.

Re: Turn Signal Problems
 

I’ve got a few symptoms I’m trying to solve

1. Lights off...all flashers/turn signals work
2. Lights on...parking lamps come on, rear flashers/turn signals work fine...front driver side turn signal and flash do not blink/flash...and the kicker...left turn indicator in dash is constant on.

I’ve read in 50 threads that I should chase down the grounds...so that’s what I’m doing

I did do an LED switch...but I got the Painless flasher modules and they work fine as long as lights are off position

Re: Turn Signal Problems
 

Ahhh ok. I'm familiar with this problem. I tried to do LED markers all the way around. I'm using the electronic flasher solenoids too. The LED tail lights work fine, but I never could get the front markers to work, probably insufficient ground. Had to keep the standard bulbs up front. Mine was 71 chevy converted to 67 GMC, but it's the same ground issue.

Re: Turn Signal Problems
 

NOOOOOO. !!!!! Say it ain’t so!!!! Surely we can overcome

Do tell more about it

I swapped the old bulbs back in....and here’s the results

1. Lights off - flash/blinker is good
2. Lights on - no flash/blinker

Now I didn’t swap the unit on the fuse block if that matters

PS...one more time on the parking light housing ground...you run a wire from the housing nut that attaches to the bumper to the frame?

Re: Turn Signal Problems
 

hmm... the flasher solenoids shouldn't matter, they're designed to work with both kinds of bulbs. It sounds like a ground problem to me. Now are you saying when your headlights are on? Or just the marker lights? You should still check the charging system just to rule it out.