Hi all, 1982 lights flickering. Wondering if alternator is going bad. No loose connections. All lights, headlights, side markers, rear tail lights, inside courtesy lights flickering at idle. Once driving not as prevalent. Also which is best way to check alternator with a volt meter? Thanks -

 

Since you have already checked for any loose connections and checked to see that the alternative belt is tight then what you described sounds like the alternator is going bad. The easiest way to check if you're getting between 13.8 and 14.3 (+/-) volts is by hooking the voltmeter up to the battery while the car is running at idle and check the voltage and also watch for fluctuation.

 

I would start with a multi-meter attached to the alternator's OUTPUT post. This should show you the output voltage of the alternator and it should give you a reading of what is heading for the battery. Measure using the DC measurement first, then check the voltage output with your multi-meter set up for AC (Alternating Current). If you see any significant amount of AC being measured then your alternator's Diode bridge is likely the cause.

Lights flickering sounds more like an alternator but on a 1982 Corvette it could be many things. As devices pull power from the battery, the voltage drops and then bumps back after the alternator charges it up again. This all happens very quickly and is the likely cause of your issues. The effect is similar to what you see on your headlights in the video.

After watching the video I would guess you might want to measure the battery voltage AT the headlight bulb. In many older cars it is not unusual to have minor changes in the lights output with the alternator voltage moving around as the battery takes the charge. The one problem many older cars have is the voltage at the headlight bulbs is much lower than your battery voltage. On my C3 I have seen less than 10 volts at the headlights and the high voltage only getting into the 11 volt range. This is why many companies offer new headlight harness' that will provide Full Battery Voltage at the headlight bulb. There is something like 30% more light when the bulb gets actual battery voltage. It is very easy to wire in a relay that would give the bulb full battery voltage and this would produce a big difference in light output.

Cleaning the bulb connections is another thing that could help improve the power getting to the bulb. I like this material called DeOxIt as it is a liquid and wipes away corrosion in a simple wipe. I tested it on the rear lights on my C3 and I was really amazed at how much more light there was coming from the cleaned socket versus the original socket next to it. The "cleaned" running light was so bright it almost appeared to be a brake light. The difference was big and well worth the effort of cleaning the electrical connections with DeOxIt!

 

Your lights should remain steady on the battery alone.
there is a volt meter in the center guage cluster. What does it say? Car turned on but not running? Now with car running, idling? Rev it up to about 2,500 RPM and now what does it read.
Sounds much more like a loose battery connection than anything else.
Check BOTH ends of the battery cables. The ground under the floor is highly likely. Then check the ground cable from frame at the idler arm to the engine block just above the starter support bracket.

 

Besides what 4vettes said, clean the connection and plug for the two wire connector on the alternator.. I had voltage fluctuations as well as inconsistent charging...Just unplugging it and put it back on would fixit for awhile, I finally broke down and spent 4 bucks on a new one...Does it do it off idle, say 1K rpms?

60

 

Thank you all - the lights on battery don't flicker. They remain steady. I will test the alternator and check ground to frame and block again. Thank you -