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Old 03-15-2026, 11:40 AM   #1
slowboy
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Turn signals and bright lights

I have a 1972 GMC P/U C1500. All of a sudden my turn signals stopped blinking and bright lights (high beam) stopped working. When I turn signal lights on they light up, but just don't blink. My low beams work.
I'm putting these 2 together because I want to know if they are connected some how. If not, I tested flasher and when I put meter to it I get a signal sound. This is out of fuse box.
My high beam switch on floor does switch from high to low when I press pedal.
Please let me know what to check on both of these problems.
Thank you
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Old 03-16-2026, 10:57 PM   #2
VetteVet
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Re: Turn signals and bright lights

check this link in my FAQs on the first page of the electrical forum , Just above where you posted.

http://67-72chevytrucks.com/vboard/s...d.php?t=681928.
Do your brake lights work? if not then check for power on the white wire on your turn signal harness. The brake lights and the turn lights work off the same filament in the bulbs. If they work, then check the front turn and marker lights to see if they come on. If they don't then post back.
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Old 03-17-2026, 10:09 AM   #3
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Re: Turn signals and bright lights

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Originally Posted by VetteVet View Post
check this link in my FAQs on the first page of the electrical forum , Just above where you posted.

http://67-72chevytrucks.com/vboard/s...d.php?t=681928.
Do your brake lights work? if not then check for power on the white wire on your turn signal harness. The brake lights and the turn lights work off the same filament in the bulbs. If they work, then check the front turn and marker lights to see if they come on. If they don't then post back.
Thanks for reply! I sprayed contact cleaner in socket for dimmer switch and also sprayed socket for blinker on fuse box. Everything is working, for now.
And the brake lights I had not checked before cleaning contacts and socket so I'm not sure if they were working or not. But they are for sure, now.

Although, my back up lights aren't working. I had them working a year ago but after several months they stopped working again. I checked wiring under rearend and cleaned everything and replace ground wire to get them working again... I think.
My steering column shift lever does not stop on p-r-d-etc. It goes either before or after each one. Plus it is hard to shift and you have to go past the P when putting in park and find the sweet spot where it'll start.
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Old 03-19-2026, 07:29 AM   #4
VetteVet
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Re: Turn signals and bright lights

Check your neutral safety switch under the column. it is adjustable. If your linkage is sloppy it may need adjustment as well.
Pull the plug on the switch and jump the two green wires together. Your backup lights should come on with key on. If they don't then check the fuse. If they do then its a NSS problem or colum adjustment problem.

I'm glad you fixed the light problem.
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Old 03-19-2026, 09:14 AM   #5
slowboy
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Re: Turn signals and bright lights

Quote:
Originally Posted by VetteVet View Post
Check your neutral safety switch under the column. it is adjustable. If your linkage is sloppy it may need adjustment as well.
Pull the plug on the switch and jump the two green wires together. Your backup lights should come on with key on. If they don't then check the fuse. If they do then its a NSS problem or colum adjustment problem.

I'm glad you fixed the light problem.
I'll try jumping 2 green wires and check fuse. I replaced NSS at the bottom of column near floorboard last spring, I think, when I worked on backup lights and got them working. Should backup lights work even if shift lever doesn't act right when transmission is in reverse?
Thanks
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Old 03-20-2026, 10:26 PM   #6
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Re: Turn signals and bright lights

The inner column has a couple of knobs welded on it that correspond to neutral and reverse and to park and they have to depress the NSS so the switch has to be adjusted so that these knobs line up with the switch plunger. If it's out of adjustment, then the lights won't lite up.



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Last edited by VetteVet; 03-20-2026 at 10:34 PM.
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