Need some feedback!

I redone the interior of my 1979 last winter and all seemed fine. Fixed many minor electrical issues and recently noticed something odd. Had the car out at night and when I put the parking lights on all the dash/center gage cluste lightsr seem to be on and working properly. My problem happens when I pull the switch to turn on the headlights from the parking light mode I notice that my speedo and tach cluster lights go out but the center console cluster lights remain on. What could cause the speedo/tach lights to go out only when the headlights are turned on but will go back on once switched back to the parking lights. Its a new light switch housing and honestly not sure if that problem was there before as I have not had the car out at night till recently so really would not have noticed. What can I look for or possible to do correct this?

Thanks

 

The DARK GREEN wire that is in the headlight switch connector is what is giving the power to the fuse in your fuse panel for your instrument lights.

Unless something got messed with during any of your electrical repairs...it makes no sense why this is going that it is doing.

The GRAY wire that goes to your speedo cluster is the instrument light wire...and is the same for yor gauge cluster also.

DUB

 

Thanks..just makes no sense...all dash lights work fine when light switch is pull out to parking lights. When I pull it out to activate the headlights the speedo/tach lights only go out..all else is fine Guess I may have to get into it and see if something got crossed or is maybe grounding somewhere!

 

I suspect that the ground wire[s] for the headlamps are in poor condition (corroded at connection points) and the headlamps are sourcing ground via the dash wiring, hence 'stealing' power from the dash lamps. There are other possibilities, but that's where I would start.

 

Yep sounds like a possibility. That I will look into. Do you happen to know where actually the headlight grounds lead to?

 

I have to agree, usually when this happens the issue is a grounding issue for the switch. Lucky for you the switch isn't that hard to get to the switch... http://repairs.willcoxcorvette.com/w...structions.pdf

Willcox

https://willcoxcorvette.com/
http://repairs.willcoxcorvette.com/

 

Thanks! Got some troubleshooting to the next couple days!

 

Two grounding points for the headlamps. One is top center of the front cowl between the headlamp door vacuum relays. The other is at the lower-left corner of the radiator support. The first is easy to get to but the other is an absolute pain as the vacuum reservoir is in the way. The one on the radiator support tends to get badly corroded

While doing some electrical repairs and updates to my '79 I discovered that once you start cleaning grounds there is no stopping. Bizarre things happen as things throughout the car find a path to those nice clean grounds via improper ways.

The front lamp harness (the one with the headlamps, etc.) has a third ground connection at the alternator. The front turn lamps have short pigtails that connect to the harness with non weather resistant connectors--it's hard to clean them with the harness in the car but it can be done.

The engine harness grounds by the starter. I also suggest cleaning all of the connectors (especially the high powered one) under the hood. You may well be shocked how much better your HVAC van and windshield wipers work afterwards! Spray contact cleaner and brass brushes work well--I ran out of contact cleaner and used some choke/carb cleaner and it too worked well.

The rear lamp harness grounds near the radio antenna.

The cabin harness grounds near the headlamp switch. If you have a power antenna there's an additional ground for its relay on the parking brake housing.

There';s a bonding ground between the birdcage and the frame near the base of the driver side "A" pillar.

 

Wow!! Thats a lot of great info! I am still trying to figure what may have giggled loose over the winter when I did the interior. I some can't get the radio antenna to jive with the car also. I can bet somewhere the ground for that came loose. Will have to locate that too.

Thanks for the info!!