Electronics flickering

[infantryman664]

Hello all!

1978 Monte Carlo Landau w/ newer 350

I have what seems to be a ground issue, but I'm having a bit of difficulty finding it. When I turn my headlights on they will change in brightness as I drive (accelerate, brake, and other common driving mechanics...it's not that predictable). It's not only my headlights though, my dash lights and stereo will do the same. The stereo will come on and off. Problem is not as severe when the headlights aren't on.

I believe (and what reading I've done seems to support my belief) that this is a ground issue. I've checked the cables at the battery and replaced the terminal connection for the negative as well as hooked up an additional ground wire from the battery to the alternator.

Where else should I check? Are there any common problem spots? Could this be something else?

Thanks for your help.

 

[drogg1]

If everything is dimming or flickering at the same time, I agree that it is probably a supply issue. This could either be a ground connection problem or a battery/alternator supply problem.

If you are absolutely sure the ground connections are good, I would check the positive wire that connects the alternator to the positive post of the battery or the starter depending on how your car is wired. If this is good, then check further downstream like the fuse block,etc. You are using a multimeter right?

Here is a link to the wiring diagrams for G bodies:

http://www.maliburacing.com/wiring.html

It could maybe be a problem with the alternator but I wouldn't think that would be as intermittent as you are describing.

 

[Rktpwrd]

I would agree with checking all your grounds and connections as listed above, but if that doesn't pan out, I would look seriously at your voltage regulator inside the alternator.
[QUOTE="drogg1, post: 488767, member:
It could maybe be a problem with the alternator but I wouldn't think that would be as intermittent as you are describing.[/QUOTE]
I'd have to disagree. I had the exact same symptoms when a voltage regulator first started malfunctioning on me on my stock 305.
It was intermittent at first, then started getting progressively worse. Do not ignore it, if it fails completely on you, you could get into an overcharging situation where you're supplying more than the proper 14.4 volts to the system, and that could lead to burnt wiring and, in a worst case scenario, an electrical fire.
Just my suggestions based on experience. Luckily for me I managed to get the car shut off and saved before any damage occurred.
Hope this helps.

 

[drogg1]

I would agree with checking all your grounds and connections as listed above, but if that doesn't pan out, I would look seriously at your voltage regulator inside the alternator.
[QUOTE="drogg1, post: 488767, member:
It could maybe be a problem with the alternator but I wouldn't think that would be as intermittent as you are describing
I'd have to disagree. I had the exact same symptoms when a voltage regulator first started malfunctioning on me on my stock 305.
It was intermittent at first, then started getting progressively worse. Do not ignore it, if it fails completely on you, you could get into an overcharging situation where you're supplying more than the proper 14.4 volts to the system, and that could lead to burnt wiring and, in a worst case scenario, an electrical fire.
Just my suggestions based on experience. Luckily for me I managed to get the car shut off and saved before any damage occurred.
Hope this helps.

Thinking more about it, Donovan is absolutely right it could be an alternator problem especially if it happens with a change in RPM. Still, I would check the charging wire from the alternator to make sure it isn't the problem. If you still suspect the alternator, I believe most auto parts store will test it for free.

 

[81_El_Homewrecker]

Using a meter you can check for voltage drops across connections and what not. This is an easy was to find bad connections like corrosion or loose.

 

[infantryman664]

Great replies, I really appreciate it! Problem is FIXED! It was a ground on the firewall. First one I checked. It was corroded all the way through so I popped off the rusty washer, took a dremel with a grinder bit, and polished the metal up. Everything works great now!

 

[pontiacgp]

It wouldn't be a bad idea to clean all the grounds. GM didn't seem to think grounds were that important. You might also want to add some grounds from the battery to the frame, body and frame. I don't think that 10 gauge wire from the battery to the body and the braided wire from the engine to the firewall do the job.