My dash light for the alternator stays on while the engine is running and goes out when the engine is not running. The car has been apart and out to the body shop so everything has been removed and has been reinstalled. Any guesses? TIA Rick
Is an external regulator or internal? Also, is it lit up bright or dim? Check the grounds first.:bglasses:
Rick, If the diodes in the alternators regulator get cooked, the light will come on, even if the alternator is still good. I drove my Wagon on a rebuilt alternator for 100k kms with that stupid light on after forgetting to put new diodes in... Did you recently rebuild the alternator, or was it dropped or apart?
Clint the alternator is not rebuilt and I don't think it was dropped. The car has been apart for about 1 1/2 years while being restored. Just getting things back together now. Drove it home from the body shop and I noticed the light being on. It is very dim prior to cranking and when it starts it goes bright. It is very dim though so dim you really have to look to see it. I still have to chase I few gremlins yet, the tach isn't working either I am thinking ground there. TIA Rick
Hmmm, it sounds like the alternator is providing juice Rick. Maybe check that the external regulator is wired correctly?
Well I replaced the regulator and it worked. Light was on when it was supposed to be and off when the engine was running. Later checking some electrical gremlins the gen light was back to it again. Light is only on when the motor is running. Noticed the alternator seemed to be awfully warm. TIA Rick
Try disconnecting the fat red wire from behind the alt. just for testing. See if it runs cooler, since it will be disconnected. Also note whether the light goes out. You may have a short somewhere. :bglasses:
Today I took the alternator done and had it checked. It checked out fine proper voltage proper amperage. Diodes checked out also. There is a procedure in the Buick shop manual to check and trouble shoot the chargeing system. As soon as I get the exhaust back on I will check that next. I am not sure where to check grounds at. The underdash seems ok. I gounded to alternator back to the battery and no luck there. Well if anything I will keep you all posted. Thanks Rick
To keep everybody posted on the light issue. I have replaced the reg and the alternator and still have the same problem. Later today I am going to run the tests from the shop manual hopefully that will give me a place to look. TIA Rick
Try running a ground wire from the regulator to the alternator and back to the battery negetive and then the body ground, see what happenns. If the light is still on, disconnect the fat red wire from the back of the alt then see if the light goes out. I'm wondering if a short somewhere is loading down your alt. :bglasses:
One more thing I thought of, you said when you replaced your regulator..........the light went out briefly then came back on again.........you may have burnt out your new voltage regulator............if you install another new one, leave that fat wire on back of your alternator disconnected until you are certain there is nothing loading it down. I hope those are lifetime warranty parts. :bglasses:
This was alluded to by Joe, but especially since the car was all apart, check to make sure all of the body grounds were hooked back up. From Engine to firewall is the most common one to disappear. I don't know about the 70 GS, but wasn't there one from the ground cable to the fender too?
Adam all the grounds are on. I even tried running grounds from the reg to the alternator, from the reg to the battery no luck. I used the shop manual and the tests say the reg is at fault. Just have to round up another regulator. I will not hook up the power lead this time and check to see if the light goes out first. I am still wondering if the first alternator wasn't bad to begin with even though it checks on the stand. Adam are you still in Montana, just checking I am trying to have this car ready by May 8 for the car show in Great Falls but we are still waiting for a headliner then it will be thrash time to get it ready. Maybe see you there. TIA Rick
Well finally got it figured out last night. There was probably nothing wrong with the alternator or regulator. After some more research in the books. There are 2 wires that feed the gen light in the dash one is brown and one is pink. When the dash was installed after painting and the plug was pushed on the pink connector did not slide on the pin, it just slid out of the connector. No contact light stays on!! Push the pink wire on and the light goes out and everything is normal. Man what a nightmare!! And that ends that chapter of the rebuild. TIA Rick
Joe when the car is not running there is voltage only to one wire (maybe battery side) when the car starts there is current on the other also (maybe alternator side) when you have the same potential on both the light goes out. Its a head scratcher had to sit down and read the manual and schematic. Sure glad its over. Thanks Rick
