Alternator problem
 

Have a 94 disco. Put in an alternator and it's not working. Checked the belt and it's right. There was a plastic cube wired to the old one. It went from the same place as the tach wire to the alternator body. What part is this and can it be purchased at an auto parts store or have to be ordered. Thanks for helping.

A noise suppressor so you wouldn't hear the whine through the radio and a phase tap resistor which protects the alternator if there is a short. Have you double checked your ground connections to make sure they're nice and clean?

I will check the grounds in the morning. Thanks.

Wait, this isn't the 'old mis-routed serpentine belt issue' is it? Better check that. 80% of people get it wrong I bet and the result is what appears like a non-charging alternator ...and the dash gauges go crazy too. Plus, it prematurely wears the grooves on the alternator pulley making the problem even worse. Do a search and you can read other posts on it. The PO of my vehicle couldn't figure out the electrical problems on mine and just threw up his hands ...took me a while to zero in on it too, but it was a cheap fix. It's so easy to overlook. Good luck.

When someone says they checked it and it's right it's decent to give them the benefit of the doubt. If it isn't then they'll figure it out eventually after a few more alternators have been swapped in, law of averages.......

belt routing
 

It was not the belt routing. The alternator was bad. Thanks.