I just replaced an alternator on my 580L backhoe, and the voltage output is reading 11.65 on the voltmeter. This is the second one I've replaced, thinking the first one was a dud. But now I am thinking it could be something in the wiring? Any one else had this issue and how did you resolve it. Thanks.
Is the alternator light on the dash working when the key is first turned to the run position? After much diagnosis I found that the light bulb is part of the exciter circuit for the alternator and it will not charge if the bulb is burnt out.
Not sure on yours, but on my old Case they used a GM alternator. Does it have one heavy wire and then two small wires on a plastic plug going to the alternator?
it does not work. Thanks for the tip!
Yes, it has
I replaced the bulb, light does not come on.
I replaced the bulb, but the light still doesn't come on with the key on.
Do you have a service manual? Check fuses, ohm meter the bulb to see if it was bad, check the bulb socket for power, it most likely comes from the key switch, so the switch could be bad. I don’t have a copy of the changing schematic handy and might be a few days before I could come up with one. Maybe someone else can help out?
The service manual does not have the electrical schematic in it. It only has a basic check list. For the schematic you would need --> Case 580L publication # 7_48712.
If it's the standard GM alternator, on the small plastic plug with the two wires, there should be cast in the aluminum of the alternator at the plug a #1 and #2. The wire from #1 comes from the light in the dash. The #2 wire is feedback for the regulator. So #2 should have 12v at all times, even with the tractor off. #1 should have 12v with the keyswitch in the on position. This brings the alternator online to charge. If you do not have 12v with the key on at the #1 terminal wire, then you still have a wiring problem up to the dash bulb. As an experiment, you can take a jumper wire and jump the #1 terminal to the battery +. See if it starts charging. If it does, you have verified your problem is the #1 wiring, and you need to troubleshoot this wire back up to the dash. You can't leave the jumper on #1 when you cut the tractor off for long periods, it holds the alternator online to charge and will run the battery down. So pull the jumper off when you are through experimenting. P.S. While you are checking things, make sure the large bolted terminal on the alternator has 12v at all times. This is your output wire. You would not think this wire would have a failure, but as the tractors got newer, they may have put a fusible link in this wire for safety, and this is easy to blow out if the battery is not disconnected when changing the alternator.