My Case 580 k alternator is not charging. The voltmeter is reading low even when the batteries are fully charged. If I flash the D terminal on the alternator it charges at 14.4 volts measured with my voltmeter. The voltmeter on the side console still reads low. When the alt is not charging the voltage on the D terminal reads zero with the key on. Measuring the voltage on the fuse panel I get battery voltage on all terminals but the instrument fuse which reads about two and a half volts lower than the rest. I don't have a wiring diagram so I can't tell if the wire from the d terminal goes to the alt light in the instrument cluster. Any help would be much appreciated
The schematic for a series #3 is here along with a discussion for similar problems. --------> HeavyEquipmentForums
Thanks Tinkerer! I will have a look as soon as we get a break in planting Brent
Hey Bud...I have 580 & 590..had similar issue as you...even after had Alt.in for rebuild..found.the D wire as you describe, goes direct to dash Alt.bulb..think it was a #94 push in bulb...after hours of troubleshooting...I replaced the bulb.All fixed working fine. Also I did an easy test with hoe running & meter on battery, jump a Hot 12v wire from bat to TOUCH the D stud.this excited the Alt.& then shows 14+ volts charging .
Thanks Tuck66, I checked the bulb and it is good but the holder and the printed circuit where it contacts is a little sketchy so I will do a little rebuilding and try it again,