Charging system
 

I have a 1973 455 in a 1966 GTO. The dash alt. light stays on. The battery won't hold a charge. How do I tell if the Alternator and Voltage regulator are working OK?


Thanks, Dave

Has this problem just started in a running driving car or did you just swap the motor and this is now happening? If the latter, are you running the 74 alternator? If so did you bypass the original external regulator? More info please, and welcome to the forum!

It would depend on how stock your electrical system is. Assuming you have the stock electrical system with the external voltage regulator on the radiator support, then try the insructions in this link, at post #9.

http://www.hotrodders.com/forum/test...or-180802.html

It will tell you if your regulator is bad. If you have the internally regulated alternator (NOT stock for 66) then your best bet is to pull the alternator and have it tested at an auto parts store.

If you have the external regulator, my guess would be that the regulator is bad. They weren't that reliable compared to the solid state gear.

Might want to try posting this in the electrical section of these forums. George Kujanski has helped many a dude with bad electrical systems.

If you want to know if the system is charging or not there two ways to test it. Start the engine and remove the positive battery cable, if it dies then the alternator or voltage regulator is not charging. The other way is to test the battery voltage with the engine off then start it up and test it again if your voltage goes up then your charging. I agree if your using the factory charging system chances are it's the voltage regulator.

Tim, I like your second test, but the first might get drobert or others in trouble. If the alternator is working, it will be at a heavy charge replacing the loss from starting the car and the battery will be gassing as its charge is being built up. Kind of the perfect storm for blowing the top off the battery. Of course if it doesn't blow up, then you know the alternator isn't charging.:p

Pull the plug from reg. take a jumper wire and on the plug go from pin#1 to pin#3 and if it is charging that will tell you the alt. is good and the reg. is bad-----BOB

How about the really lazy way?

After I put my car together the light was on, so one of the first things I did after the initial test drive was to stop by the local Advance Auto. Most of the local parts stores still have the test equipment to check our old charging systems and they will do it for free in the parking lot. My problem turned out to be the voltage regulator. I replaced it right there on the spot using their tools and have had no problems since. That was 3 years ago.

It was actually a fun way to show off my new engine and detailed engine compartment.