I've got a John Deere 310D backhoe, no cab, 2 wheel drive. The water pump started leaking the other day so I took it in to be rebuilt (YIKES!!) While it was down, I serviced it, blew the dust out of the radiator and alternator, etc.. Put the water pump and V-belts back on. Started it and the ALT light stayed on and the TACH did not work. Checked it out while it was running and it was pulling around 12 amps. Shut it off, and it was showing 12 amps. Checked all fuses, etc.. Took the Alt. in, had it checked out. Brushes worn, needed replaced. O.K. Installed the new one..... SAME PROBLEM. Any idea what could be wrong?? :Banghead I sure appreciate any help. Many thanks.
What is showing 12 amps? and what did you set the tension on the belt to?
Is it a Delco or a Bosch? There are a couple of wires to check for 12 volts with the key on.If it is a Delco check the little clip on connector to the top of the alternator.With the key on you should have 12 volts going to them both.If it is a Bosch then there should be 12 vdc at the D plus.If not then check the fuse (F1)or the diode inline .It looks like a blind connector on one of the wires going to the alternator.With your ohm meter check to see if you have continuity in one direction.And make sure you have all the wires hooked up the same way they were when you took them off including the ground. I agree with Delmer that if you have a loose belt then the tach(purple wire going to the alternator)will not read or it will be jumpy.Oh yeah,I think you have your volts and amps mixed up.