Charging system light stays on

I have a delema here!

I have a 1986 GM Wagon 5.0 liter Auto w/overdrive.

I've gone through the normal diagnostic of replace to see if it works.

I've replaced the Battery (Old one was old and weak 385 CCA)

I've relaced the Battery cables since the positive cable was the original and the negative had a funky replacement terminal and neither looked very good.

I've replaced the Alternator (due to Daughter hooking up the jumper cables backwards)

Have had the system checked after all of this and the test comes back positive everything is ok, battery CCA=875 alternator output =14.4 Volts, the Alternator diodes test out good.

The only thing I haven't replaced is the Serpentine Belts that are a bit old but look good, (which is next to be replaced)

The AMP light still remains on (driving me buggy)

Is this problem possibly related to the computer? all other lights work properly and no other apparent problems other than just being old.

Marco Sr.

How about the voltage regulator? If it’s external you might want to change that too, since something could have gone wrong with it also.


I have a delema here!

I have a 1986 GM Wagon 5.0 liter Auto w/overdrive.

I've gone through the normal diagnostic of replace to see if it works.

I've replaced the Battery (Old one was old and weak 385 CCA)

I've relaced the Battery cables since the positive cable was the original and the negative had a funky replacement terminal and neither looked very good.

I've replaced the Alternator (due to Daughter hooking up the jumper cables backwards)

Have had the system checked after all of this and the test comes back positive everything is ok, battery CCA=875 alternator output =14.4 Volts, the Alternator diodes test out good.

The only thing I haven't replaced is the Serpentine Belts that are a bit old but look good, (which is next to be replaced)

The AMP light still remains on (driving me buggy)

Is this problem possibly related to the computer? all other lights work properly and no other apparent problems other than just being old.

Marco Sr.

How about the voltage regulator? If it’s external you might want to change that too, since something could have gone wrong with it also.


Well it's an internal Voltage regulator and it tested good when they tested the rest of the charging circuit.

Thanks for the reply, I'm still hoping someone might have some clue as to what is causing this problem.

Marco Sr.

Just as un update for this message, I finally got upset enough and demanded another new Alternator since in my opinion that was the only thing that could have caused that problem, I was right the alternator was defective while it tested out correctly for the voltage it was the amperage output which was where it was failing.

The people at the local parts store couldn't understand why thier tester didn't catch the problem, they have one of these 500.00 testers that supposedly checks everything! So I told them it obviously doesn't check for amperage output otherwise it would have caught the problem.

My personall opinion is that while that tester works on most of the newer cars because the dashboard indicators on the newer cars are VOLT meters/light not AMP meter/light like this old GM has.

Well it's an internal Voltage regulator and it tested good when they tested the rest of the charging circuit.

Thanks for the reply, I'm still hoping someone might have some clue as to what is causing this problem.

Marco Sr.