Need some help figuring out a bothersome electrical issue on my ’69 Cutlass. GEN light is coming on very dimly. Good news is the charging system appears normal. I replaced the alternator and VR within the last year. Voltage at the battery reads 12.7V engine off and 13.9V at idle so not sure why the GEN light is coming on, maybe a bad or corroded connector going to the idiot light. Also the voltmeter in an aftermarket 3 gauge cluster reads around 13V. It has always shown a bit lower than what I measure at the battery. Any ideas before I blindly dive in this weekend?

I know most of the country is ice cold right now but we are having mid-70's convertible weather in Texas now. That is rare for January even down here. Enjoyed driving today but uncovered this issue.

 

Is the belt tight? Do you have any aftermarket electronics that could be drawing more than your alt. could handle?

Larry

 

The idiot light does not use a ground on one side. If there is equal voltage on either side of the bulb then the light will go out.
When one side has more/less on one side then the light will glow. It depends on the voltage difference as to how bright it will glow.
You state you have 13.9v at the battery but 13.0v inside the car. That means you have almost a full volt difference allowing the light to glow slightly.
Read this article I wrote and check all the connections at the bulkhead connector.
Joe

http://temp.corvetteforum.net/classi...ternator.shtml

 

This article is very good. Could be a sticky. Excellent starting point.

 

Thanks for the link. I'm hoping it is the wiring between the alternator and VR on the bulkhead as you mention and not anything behind the dash. The 2 wire connector at the alternator is a little wobbly so maybe that is it.

 

do you have a voltage regulator,I had a regulator going out when i had this issue also.

 

Cleaned the connections at the alternator and VR. GEN light went out but came back on later. Jiggled the wires are it went off again. Looks like time to repair or replace the connectors. Checked the under dash voltmeter and it is reading about half a volt low so not as much difference between voltage measured at the battery as indicated. Thanks for the advice.