I think my voltage regulator is dying, just wanted confirmation before I replace it. This is an '85 V12 with a stock 75a Lucas alt.

I oticed today while driving around the gauge on the dash showed no charge, 12v. Pulled over and checked voltage a the battery, up, 11.8v (no Jag owner should ever leave home without a multimeter).

A couple minutes later the dash gauge came back up to normal. It cycled like this a few times on the ride home, intermittently charging. The battery warning light did NOT come on when it wasn't charging.

The switch between charge and no charge didn't seem to be in response to anything happening, like hitting a bump, wiggling the exciter wire, turning the lights on, idling or revving it. Pretty random.

Occasionally, but not always, when it would start to charge (while driving)the dash light would come on briefly, as thought I had just started the car, and go out after a couple seconds.

Thoughts? A voltage reg is pretty cheap but pointess to install until I'm pretty sure that's it.

Thanks,
Darel

 

It very well could be. When mine had a similar issue I had trouble locating anything other than Chinese junk for replacement parts. I bought a rebuilt with lifetime warranty from one of the Walmart type parts stores. After 3 replacements in 6 months I bought the John's cars bracket and picked up a used GM alternator and rebuilt that and it has been working great for 6-7 years now. I think mine is a 94 amp unit now.