Gauges acting funny

[SlyMart]

I recently replaced all the light bulbs in my center console last month and yesterday it was the first time I drove the car at night. During the night while my headlights were on I found that the dash lights including the center console were very dim. I even turn the headlight to max and still very faint. I noticed that my oil and gen gauges acting weird when my headlights are one and when I turn my headlights off those 2 gauges goes back to normal. Is that a short?

First picture : headlights are on.
Second picture : headlights are off

 

[hezzy]

I recently replaced all the light bulbs in my center console last month and yesterday it was the first time I drove the car at night. During the night while my headlights were on I found that the dash lights including the center console were very dim. I even turn the headlight to max and still very faith. I noticed that my oil and gen gauges acting weird when my headlights are one and when I turn my headlights off those 2 gauges goes back to normal. Is that a short?

First picture : headlights are on.
Second picture : headlights are off

No. I don't think it's a short.
I actually think that your battery might be going. Or the alternator. When the headlights are on the alt. Has to work harder to charge the battery. When either is going bad you will see a drop in power at the guage like yours. As far as the oil pressure... when you turn on the lights does the RPM drop? If it does that would be why that pressure drops.
That is my humble opinion.
I hope it helps.

 

[buckhorn76]

start checking grounds too.

 

[SlyMart]

Thanks guys I will check it out this week.

 

[Brian Keery]

Incandescent bulbs or LED's?

 

[SlyMart]

replaced the bulbs with the same ones the factory uses.. Even the instrument panel light which I haven't changed is very faint unless they are like that at the factory.. Can someone take a picture of their instrument and center console at night without their flash and 1978 corvette also.. I will buy a battery and a alternator this week..

 

[Brian Keery]

Whoa easy up a minute. Before you start spending money at buying new components, let's troubleshoot the problem. The alternator and battery outputs can be checked in your driveway with a simple voltmeter. Verify your initial battery voltage, charging output voltage at the alternator and the battery. Then turn on the lights and see what the output is at the alternator and what the battery is seeing as charging voltage. You did replace the circuit board at the gauges and the gauge lights, as well as the clock - anything else in that area? Buckhorn and I seem to be very methodical in our troubleshooting logic; so I would side with him and initially suggest a ground issue. Check your voltages and get back to us.

One more thing, did you get the opportunity to run the car at night before you started the mods? The reason I ask this question, is do you have a 'baseline' to compare the lights to? Also, when you turned the light knob did the dash lights dim to nothing and then come back up?

My lights seem to work fine (they're exactly the same as your's), but they're definitely not as bright as my DD.

Get some data, and get back to us. I'm sure we can figure it out.

 

[hezzy]

Whoa easy up a minute. Before you start spending money at buying new components, let's troubleshoot the problem. The alternator and battery outputs can be checked in your driveway with a simple voltmeter. Verify your initial battery voltage, charging output voltage at the alternator and the battery. Then turn on the lights and see what the output is at the alternator and what the battery is seeing as charging voltage. You did replace the circuit board at the gauges and the gauge lights, as well as the clock - anything else in that area? Buckhorn and I seem to be very methodical in our troubleshooting logic; so I would side with him and initially suggest a ground issue. Check your voltages and get back to us.

One more thing, did you get the opportunity to run the car at night before you started the mods? The reason I ask this question, is do you have a 'baseline' to compare the lights to? Also, when you turned the light knob did the dash lights dim to nothing and then come back up?

My lights seem to work fine (they're exactly the same as your's), but they're definitely not as bright as my DD.

Get some data, and get back to us. I'm sure we can figure it out.

AGREE !! dont go blowing money needlessly.
you can and probably will spend a ton any way....
Yes just simple checks to verify voltages and you will be glad you did.
Ive been very wrong before with my own money pit and could have saved $$ by simple checks

 

[SlyMart]

I will change the battery and the alternator since I have no clue how old they are.. if I change the battery and alternator at least I would know that they are new. I never want to be stranded on the side of the road because I tried I ignored the signs. My car is 37 years old and I should at least change the important parts that could prevent me to be stranded and then spend more money to get my car towed for a flat bed truck.. I know what I was getting myself into when I bought this car and at least this car has better value than my old cavalier z24's.. Believe me I spent alot of money on my previous cars which it was a waiste of money.. The corvette in the other hand is an investement..

 

[Brian Keery]

I wouldn't be aimlessly getting rid of potentially numbers matching equipment, that if faulty could be rebuilt for a fraction of replacement cost. Especially on an investment Pace car. Your car, your choice. Sincere good luck with your issue. Hope you figure it out.

 

[SlyMart]

I don't need to worry about numbers matching since the previous owner put some hooker headers on it and converted to true dual exhaust with some flowmaster mufflers..

 

[Black 03 Z06]

Sly Mart, you don't have much choice if the battery is done you will have to replace it. I would however ask around to see if there are any shops that will rebuild your alternator. It is not so much a numbers matching thing but there seems to be a lot of quality issues with some replacements. Just remember the old adage of replacing one thing at a time when trouble shooting. Checking the voltage as others have suggested will tell you a great about what is happening.

Good luck sorting it out.

 

[nascar03]

SM... ALL good advice here.....
Most faulty alternators of that vintage just need the diode trio replaced.
It is a $10 part. Local electrical shops can service it quite cheap or DIY.
They can also perform a load test on your battery.
Do a voltage test on the alternator first after the battery is replaced.
I think perhaps you have a grounding issue in your dash.
I am chasing some electrical issues in my C3 dash as well.
Graham

 

[buckhorn76]

if your car starts without a boost then your battery and alternator are okay. that is a much larger power draw than the dash lights - think about it. like i said before, start checking grounds, the c3's are notorious.

 

[wildone909]

Had the same problem with mine... dim lights and inacurrate gauges when I turn my headlights on.. Mine was just a ground problem. Troubleshoot first as others have said .. replace parts later

 

[SlyMart]

I ended up buying a brand new battery and new alternator but I kept the original one.

While removing the old alternator I examined the plastic connector and the ground wire is like half the wire is connected. So that might the original problem that I am having. So I ordered the wire and this should fix the problem.

 

[Keith Tedford]

With any old car, the best fire insurance you can buy, is an all new harness. They get old, dried out, cracked, corroded and messed up from mishandling. That's not to mention what mice can do. It's amazing just how bad things can get but are not obvious until you take a real good look.

 

[Riley P]

When Taylor (Taylorsk8) was taking apart his '73 he told me the wiring harness in these cars were only designed to last 10 years (I think it was 10). 40+ years and many of these cars are still on the road. When I had my 66 Chevelle (Jeeze, I'm starting to sound like you Keith, talking about my old Chevelle ), I kept a fire extinguisher in the car because with storing it each winter, you never knew if a mouse chewed through something or when a wire was going to get hot.

Glad you found the problem! Let us know if replacing the wire fixes it!