Electrical Diagnostics Help

[mhuppertz]

I have been unplugging the alternator plug every night to keep the battery from draining. When I plug it in the next day the A/C clutch engages right away with a loud 'click'. I have run the wires but I can't find any abraided areas. I haven't replaced the alternator yet because I have the sick feeling it is something else.
I'm starting to think that there are just mutliple issues giving confusing and conflicting symtoms. It's possible the alternator has an issue that is feeding power back into the PCM and making it do weird things.
Anyone have any ideas???
Thanks,
Mark

[moab4x4]

I know this sounds dumb, but is there anything else powered on when the truck is off, heater blower, radio, etc? I almost sounds like the ACCY circuit is not shutting off when the IGN does. I'm not looking at my FSM, just shooting from the hip on this one. Ignition switch comes to mind. On the other hand, I would have looked where you did for a short on the ALt Batt lead to the AC clutch lead.

I had one like this that drove me mad until I installed a high current relay on the line to the alternator and switched it with the IGN. Kinda jury-rigged, but it worked.

[Philip]

There are two plugs two plugs to the alt which one are you unhooking?

[mhuppertz]

There are two plugs two plugs to the alt which one are you unhooking?

It's the one laying on the fenderwell liner, passenger side very close to the alternator. It's the only plug I know of for the alternator.

[mhuppertz]

I know this sounds dumb, but is there anything else powered on when the truck is off, heater blower, radio, etc? I almost sounds like the ACCY circuit is not shutting off when the IGN does. I'm not looking at my FSM, just shooting from the hip on this one. Ignition switch comes to mind. On the other hand, I would have looked where you did for a short on the ALt Batt lead to the AC clutch lead.

I had one like this that drove me mad until I installed a high current relay on the line to the alternator and switched it with the IGN. Kinda jury-rigged, but it worked.

I have thought about the relay thing also. I hate to do that because I really want to know what is going on.

[Philip]

Ok I went threw my charging and speed control manual. The only place I can see where the A/C and alt come togeter is the ASD relay. But it is in the off state with the key off. That means the alt is back feeding power threw the ASD relay circuit. That is the only way the A/C clutch would come on.

Relace the alt.

[PToombs]

Unless the ASD relay is bad, or still getting activater power from someplace. I'd double check the relay for power, just in case.

[mhuppertz]

Well, I swapped the ASD and the A/C relays and the compressor clutch clicked off, and the voltage stabilized. The real test would be to start the truck and run the air, then turn it off to see if the clutch stayed energized.
Oh, it will, I guarantee it!
Interestingly, I unplugged the ASD relay first and nothing happened....
The plot thickens.