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1980 Chevy k20 lights issue

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Dec 14, 2016, 11:58 AM

Post #1 of 4 (463 views)
1980 Chevy k20 lights issue Sign In

I have an old 1980 chevy with a few issues and need some help. One of my front headlights works high beam, but doesn't work low beam. The other one works on both. I tried replacing the headlight with no success. What's my next move here? It seems like it shouldn't be a wire issue since high beams work.

I'm also having a similar problem with my rear passenger blinker. The taillight and brake function work, but the light will not blink. All other blinkers work, including front passenger. Blinker and 4way doesn't work on the one light

Someone mentioned it could be a grounding issue. If that is the case how/where specifically do I check that.

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 14, 2016, 12:42 PM

Post #2 of 4 (449 views)
Re: 1980 Chevy k20 lights issue Sign In

This is going to require some electrical testing that it doesn't sound like you have the equipment or experience to do yourself. It's probably a job for a shop that does electrical work.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Ultimate Carjunky / Moderator
Discretesignals profile image

Dec 14, 2016, 5:18 PM

Post #3 of 4 (423 views)
Re: 1980 Chevy k20 lights issue Sign In

If you have a 12 volt test light or a volt meter, you can test the circuits to see what is missing. The left low beam may be missing power because the low and high beams should share the same ground on those. If the high beam is working more than likely the ground is good there. You will probably need to get hold of a lighting diagram for that. Might get lucky with a Chiltons or Hyanes.

There should be three wires on the head lamp connector. One is ground, one is power for low beam, and the other is power for high beam.

I believe the brake and rear turn signals share the same circuit from the turn signal switch back. If both brake lights work, that eliminates the wiring and bulbs to the lights in the rear. There might be an issue in the turn signal switch itself. You can test that with a volt meter and wiring diagram also.

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Dec 14, 2016, 5:21 PM)

Tom Greenleaf
Ultimate Carjunky / Moderator
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Dec 14, 2016, 8:30 PM

Post #4 of 4 (416 views)
Re: 1980 Chevy k20 lights issue Sign In

I'm in trouble because it's a truck! Is sealed beams not certain if all were large single or 4 lamps in all? TMK headlight switch was a pull knob, high beam selection sill on the floor button not a multifunction switch for MY 1980 but close.

Educated guess with both headlights and directionals (blinkers) both have an issue the common item would be the headlight switch or plug to it.

Problem: Truck - who messed with what already over all those years? Trailer wiring was NOT included that I know of or an option. No third/high mount brake light.

This is probably only going to be a test this specific vehicle in person noting condition of wiring and what might have been altered.

Very slight chance the rubber block of wires at firewall has been removed and not connecting well right there. OE was packed in white grease which would be just crust by now.

Tough one without being there - again especially a truck,


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