I've been blessed with a parasitic drain on my battery that will kill it in a few days. I did a baseline test with my ammeter and something is pulling about 200ma. I did the usual "pull-a-fuse" test and had some interesting results. I pulled every fuse and the drain on the battery remained the same (about 200ma). However, when I pulled the C/H FAN fuse the milliamps jumped to about 500 and I could hear the alternator whining. I disconnected the alternator and the milliamps dropped to 21 Pulling only the HTR A/C resulted in the same thing, 600ma and the alternator buzzing. Unlike the C/H FAN fuse, disconnecting the alternator only resulted in reducing net drain to my baseline, about 200ma. If I pull both of these fuses with the alternator disconnected the drain is 21ma, which is ideal from what I've read. I have no idea of where to begin searching. I imagine those fuses are somehow related. Anyone have any ideas?

 

ttt. Anyone have at least a clue what this could be? Does this sound like a short, bad relay/switch, broken wire, etc? At this point I'm up for any suggestion

 

Wait until late at night when all is very very quiet, and stick ear against hump in trunk, and see if the fuel pump is running. My 305 TBI had a bad oil pressure sending unit, which caused the fuel pump to run constantly, even with the key in my pocket. I couldn't ever hear it with the normal daily street noise, but late one night I heard it humming in the trunk, and Viola!

May not be the answer - but it's something to try.

 

The Heater AC and fan all get there power distribution from the starter B+ terminal. I would check the wires at the starter first and work my way up. But i would suspect that the alt is staying "turn on" You might try getting the alt checked. Unless you have some major stereo equipment in your ride thats where i would start.

 

The reason that you are hearing the alternator buzzing is because the brown (tan) wire from the alternator goes to the "C/H FAN" fuse which is also linked to the starter through a fusible link as mentioned above.

 

Thanks, I'll check those wires first. The alternator is "new", I recently replaced it, but I can double check it. Should I check for voltage from the alt connector with the engine off? I'm assuming the wires to the alternator should not be "hot" with the ignition off.

Could you explain why pulling that fuse would would cause the alternator to buzz (I'm an electrical newbie), it doesn't buzz with it in? It looks like checking the brown alt wire would be another wire to check, correct?

 

There should be 3 wires that come off the alt. One large one that goes directly to the battery (hot all the time) and two smaller ones that are in a connecter. The two smaller ones are the ones that excite or turn the alt on if the voltage drops. the smaller tan or brown one should be hot all the time and the other, red i think, should be hot with the key on. Some times the internal regulator in the alt can be stuck on and would cause a draw on the system. This is easly checked by unpluging all the wires that go to it.

 

did u ever find your problem??
i have the same problem u did.