Non working voltage regulator

replaced dead battery. after driving a few days–low voltage on battery, had to charge. took to local Auto shop for test and the alternator was not good--------years ago installed a -GM A-130 alt where the air pump was. put in new alt. just for my satisfaction had the test rerun. alt is working, but according to test, the voltage regulator was not working… – also the amp gauge on the dash does not move with everything turned on–never noticed before. called my supplier and it was stated that the reg was built into the OEM ALT…is there a REG that can be added or do i have to go back to the OEM alt. still have the old alt on the shelf, can possible to have it rebuilt or, almost $300 to go back to the original. which could be a pain for drive belts, being that there is no air pump-----Michael 85 XJS

If your alternator is the IH A130, you could use the IH regulator- on GM built vehicles the regulator function is done by the powertrain computer. Chrysler Performance Parts also has an external regulator that could work.
The question I have is how did it work “for years” previously? Why not just replace it with a 3 wire GM 10SI alternator that has an internal regulator? They are available in any amperage and I’m pretty sure that they mount the same.
Lack of the air pump would have no effect on the OE alternator as it is driven by it’s own belt (not the air pump belt). The a/c compressor won’t be happy though…

every thing good–alt has internal regululator. my master mechanic tested it and all is good— had same alt for years, just gave up.—charge gauge in dash is still not working
what happened to web page…when accessed it is just a blank white page—just tried to VISIT TOPIC, same results–blank white page thanks, Michael 85 XJS
ps–gone until 10-1

It’s magic. This magic is related to the condition of the brushes and slip rings.
In the history of Great Indestructible Vehicles - the only parts in need of replacement (usually every >100k miles) were:

  • cam belts
  • water pumps
  • batteries
  • alternator/regulator brushes and slip rings
  • starter motor

More details below:

Oh, and by the way - broken lightbulb in your dash will prevent alternator to receive “priming” power to alternate. It won’t work at all. Start from checking if tiny cable provides power to the unit…