I am confused about the layout of the charging circuit for the case 580c and hoping someone here is more familiar with it. When looking at figure 14 - charging circuit, it shows the green wire for the alternator warning light joining the same post on the key switch as the red wire from the 40 Amp circuit breaker. However, in the wiring diagram titled 'power shuttle wiring diagram, early production', it shows that green wire for the alternator warning light joining to the same post as the wire that connects to the push button starter. Both diagrams are from the same service manual. I figure it has to be one of these, or I am missing something, or perhaps it doesnt matter which post the wire is on? What brought this to my attention is that my alternator warning light does not illuminate when I turn the key switch to On with the engine not running. It is supposed to do that along with the oil pressure light (the oil pressure light does work how it's supposed to). My alternator is charging the battery when it's running, and I have double checked the bulb and made sure its working and even tried other bulbs. When checking into this issue of the bulb not illuminating, I realized I have my green wire joined to the post on the key switch with the same wire that leads to the relay (the number 5 wire with the number 11 wire in the diagram, I'm guessing that's the 'accessory' side of the key switch). I rewired this machine myself from scratch, including new key switch, and everything has been working fine except the alt warning light not coming on when it's supposed to and I also have a slow ghost draw when the machine is off that drains my battery after a few days. I'm beginning to think now it's because I have my green wire on the wrong key switch post and need to figure out what post it's supposed to be on. I also installed a battery disconnect switch when I re-wired the machine so that's how I keep my battery from getting drained overnight
The one diagram is wrong. I know OEM's make mistakes in their manuals, Ford is bad about it. But I guess case does also. Terminal #1 on this GM alternator brings the alternator online to charge with the key. That one should run to a light bulb WITH TWO WIRES, no ground. The other side of the light is wired to the key on ignition. When you turn the key on, but do not start the engine, the light burns since there is 12v on the keyswitch side, and nothing on the terminal 1 side. When you start the engine, 12 volt appears on terminal 1 if the alternator is functioning properly. 12v on the keyswitch side and 12v on the alternator side of the bulb will make the bulb go out. Terminal #2 is the voltage feedback for the internal regulator. The internal regulator monitors terminal #2, and it uses this to judge the output of the alternator. It's hooked to a hot 12vdc in the system. Most people just jump terminal #2 to the large output wire of the alternator. But the factory sometimes runs this up in the harness somewhere to sample the voltage at a different spot in the system. I did a google search on GM alternator wiring, and you can see people use this same alternator on their old cars and trucks, and you can see how it's wired. I actually have one of these on my 1984 Ford Bronco II for charging purposes.
Ok, so I have my alternator wired exactly like the image for figure 14, where #1 terminal is jumped to battery terminal and #2 leads to the lightbulb. Youre saying I should switch the #1 and #2? Also, should that wire that runs from the lightbulb go to the battery terminal on the key switch or the ignition terminal that the wire for the push button starter is on? I feel like I have switched the wires for #1 and #2 terminals on the alternator before and had no change, but that could have been because my keyswitch was wired incorrectly to begin with. I have been dealing with this issue for a long time. I kind of put it on the back burner though because my alternator is charging the battery when running and I just use the battery disconnect to prevent it from draining overnight because it was a quick fix. Still would like to get to the bottom of this lol. Thank you for the reply
The light bulb must be on the key on ignition hot. If you put it on battery hot the alternator will be a drain on the battery. And all this is on terminal #1. Terminal #2 is the one that is jumped over to the output lug.
Got it! It was exactly as you said, franklin2. Turns out my key switch was wired correctly and I just had to switch the terminal 1 and 2 wires on the alternator. Light comes on now and no more battery drain. Now I'm going to make the corrections in the service manual incase my children or nephews run into this problem one day Thank you again for the help with this, I would have never figured this out and I have been banging my head against it for awhile now. Who would have thought the service manual of all things would be so wrong. What an absolute gem this forum is. I have learned so much over the years just lurking here. Thank you all for sharing your knowledge