Alternator or V-Regulator question
 

OK, took the car out for a drive the other night and the stereo started acting up, then the lights (evening was just falling). Got it home and the battery was real low. Charged the battery up to 12.6 overnight.

Started the car and the voltage held at 12.2. Took the RPM's up to 2000 and the voltage across the terminals stayed at 12.2 no increase. The alternator light does not come on.

According to Bentley, this indicates the voltage regulator is at fault. Is this correct, or did I miss something? Should I replace the alt and regulator? Does a reman Bosch come with a new regulator?

Apologies for all the questions, but I really don't want to spend the extra $$$'s if it is not needed. I know with the knowledge bouncing around this board the answers will probably be right on the money.

Thanks in advance,

Fred

Does the light work with motor off but ignition on? If not, replace it. It's part of the charging circuit.

Joe Bob,

Thanks for the quick response.

Ignition on/motor off, light is out. Will replace the bulb and let you know. Thanks for the catch.

I agree it is the VR....I just had this happen
You can replace only the VR but it is bout $80

Your best option would be to take to a local Alternator shop and have them rebuild yours....should only cost 100-150

Just pulled the bulb. The element looks fine and there is continuity through the bulb, but it does not come on.

Update confirmed bulb is good, went to put it back in the tube and the metal on the bulb touched the metal on the tube and the bulb lit right up.

Check your voltage again when running. Should be closer to 14v and remain steady.

Bob,

No luck, without that mistaken contact the bulb does not light up. Even with it lit (mistaken contact being kept to keep light on) , the voltage stays constant while the engine is running and drops by a couple of hundredths when RPM's are increases.

There is one other easy check to make and thats the earth wire to the fuse/relay panel in the engine bay on the lhs. If you have a regulator mounted on that panel and the panel earth wire falls off the alternator stops charging and the idiot light stays off. (The panel is rubber mounted) Of course if your regulator is on the rear of the alternator then this does not apply. Pull the alternator and check the slip ring brushes before you visit the auto electrician or order another alternator, bushes are another cheap fix if the bearings etc are still all good.

In your '88, the VR is integral to the Alt. Get a new one or rebuild the one you have, I'm not sure you can replace the VR alone, but a rebuild shop probably can.

The dancing banana says the bulb is integral to the system. A couple of hundredths is all the variation you should see. What is THE voltage?

SUCCESS!!!! I finally broke down and bought a new (reman) alternator from PP. Or more correctly, my wife told me to get off my tight a$$ and get a new one. Installed it, the light is working correctly and the voltage across the the terminals is 14.2 - 14.35.

Good going! Thanks for posting back...