Tachometer started acting goofy and playing dead. Also, the Battery Charging light illuminated whilst driving.
Ordered regulator off eBay. Was sent an IX128 ('94-'95 D1) instead of an IX123 ('96-'99 D1). Seller accepted return w/ no problem.
Dropped alternator off at rebuilt shop. They ordered the right regulator and had it back to me with new bearings the next day. $50 out the door.

 

Was that the problem?
Make sure you are routing the belt correctly ....about 90% of Disco owners mis-route it at some point and experience the SAME symptoms as you. THe way you'd 'think' it should go on is the wrong way (believe me). Look up and be sure you have it right. If you get it wrong it'll wear the alt pulley out from slippage and you'll need to get a replacement.

It's funny ...I took my alt to an alt shop and the owner hooked it up ...did some testing. While he was looking for some clips I look back and the alternator is SMOKING!! Holy Crap!! He runs back and unhooks it ...it was HOT. Anyway ...he made it right for me... "These alternator shops always do GREAT work, huh??"

 

Yes, that was the problem.

I got the belt routing figured out long ago (wrote it on the rad. support). Had a copy of the rave in the truck when I got it. One of the first things I replaced was the belt, twice. Not because of belt routing but Dayco belt was squeaky. Went with a Gatorback, no complaints.

I've been using this auto electric place for over 16 years for work and personal stuff. This one has done very good by me . I am the one who ordered the voltage regulator off eBay before I took alt. off truck. Gave it to the shop after hearing the bearings when spun by hand.

BTW, the belt routing seems instinctive to me, how do folks route it wrong?

 

Those brushes were worn to a nub! BTW, what did they do for $50? Were the commutator's worn or still good? They're pretty easy alternators to rebuild. I'd say you got a good deal though because it still takes time.

I don't know what it is with the drive belts. A lot of mechanics seem to make that mistake too it seems. Would have been an ingenious idea by L/R to put a sticker on the core support like every other manufacturer in the WORLD!!! Or better yet, design it right the first time so the belt can ONLY fit on one way. Whew... got that out of my system. Mine was mis-routed when I got it (that's why they dumped it -- couldn't fix the electrical gremlins), and even when I did it once, I found myself wanting to install it with the top of the belt going straight across the top to the alternator even though I knew it shouldn't.

Just stick around and you'll read a lot of posts about alt belt routing. The good news is it is an incredibly easy fix for otherwise flaky problems when it is the case. It was a good idea to draw yours on the radiator support. I might do something like that..

 

They replaced the bearings, cleaned commutator (wasn't as bad as he initially thought), and the voltage regulator. The price I received was probably a favored customer rate.

Would like to see a negative of this in 1.5" square sticker. Sharpie worked though.

 

My Photobucket doesn't work since they started charging. I put a Negative in the gallery:

 

I don't get how someone could misroute these belts. Can't see how it's possible but from reading it's apparently epidemic level. Bizarre.

edited to add: after looking at the diagram again, like all belt routing you're gonna HAVE TO go around the outer pulleys, then you're left with the two, one being the tensioner and that's a no brainer. Last pulley becomes self explanatory.

 

Thanks Mark. I use Infraview a lot. Haven't bothered making it into a vinyl sticker though.

Rob, me too. Only thing I can think of is coming off the right of the crank and then around the water-pump.