I've been chasing down a slow current drain in my '75 j-10. The battery will go dead if I don't drive it for 2 weeks or so. I started disconnecting the battery cable and noticed when the key is off and all other accessories are off, I get a little spark at the battery post when I reconnect the cable, which tells me something is using current. So I pulled all the fuses, unplugged the ignition and the headlight switch and horn relay and steering column harness. I still got the sparking. I then undid the #12 red wire from the alternator post-no more sparking. Should it be drawing current like this? It's a delco alternator (someone changed it over from a Motorola) and I was wondering if it was defective. Thanks
Chris

I agree, there is some type of current draw on the battery. There are a couple ways a Delco alternator can be wired, some wiring methods are better than others. My guess is some wire connection from the old Motorola wiring might be the cause.

The Delco alternator only needs three wires to keep the battery charged. Two of the three wires will be connected to the battery, so it's easy to convert to a Delco alternator. On the back of the Delco alternator is a terminal marked "BAT" this is usually a 10 ga. or 12 ga. wire going to the vehicle battery. There are two side terminals on the Delco alternator marked "1" & "2". The "2" terminal can usually be connected to the "BAT" terminal on the back of the Delco alternator with a 14 ga wire. The "1" terminal wire can be the most difficult wire to get wired correctly. On GM vehicles, the "1" terminal gets wired to one of the alternator warning light wires, with the other alternator warning light being wired to the "ON" position of the ignition switch. My guess is someone might have wired the "1" terminal to have battery voltage all the time, which would drain the battery.
dave

Ok, hees the way it's set up now. The #2 terminal goes to the battery side of the starter solenoid. The #1 is a little strange, it goes to a lighted switch that just hangs next to the battery and from there it attaches to the yellow wire of the old voltage regulator connector. This was all done by a previous owner. He said that switch had to be there to sense voltage. I never fooled around with it because it did charge ok. On my facory wire diagram sheet, it shows a 10 ohm wire on the #1 terminal, but it doesn't show where it connects. It ends at the firewall junction. I would like to get rid of that lighted switch if I could. Thanks for your response.
Chris

Hey Chris,

Curt here. Long time no talk.

When I bought my truck someone had tried to convert to delco and did so wrong. The battery ran dead. I went to Autoelectric on sunnyoaks and they, for free, told me how it should be wired. I did so, which was VERY easy, and I have had no problem since. My truck can sit for weeks and fires right up. Charges perfect. If you want to come over and take a look give me an email. I will be leaving duck hunting friday and will be back sunday afternoon.

later
Curt

A lighted switch, well that would work. I can only hope the power source for the lighted switch is from the "ON" position of the ignition switch. I'm wondering, would this lighted switch "GLOW" when the engine was shut off? I'm also wondering, would this lighted switch "GLOW" with the engine shut off, but with the ignition switch in the "ON" positon? I was thinking that maybe the lighted switch would "GLOW" when the engine was shut off, reguardless of the ignition switch being, "OFF" / "ON" which would drain the battery after awhile.
dave

Yes, the lighted switch is only on when the ignition in the run position and engine off. I've done some searching on the other boards and found that my lighted switch acts as a crude idiot light. (Later j-series have no idiot lights). I scrounged up a red dash light so I'm going to put that next to my aftermarket voltmeter and do away with the switch. The #2 wire is on the battery side of the starter solenoid, so I'll leave that where it is. There seems to be a wide range of opinion where this #2 wire should go. I keep hearing battery post, solenoid post, horn relay, or looped to the Bat terminal on the alt. At this point, I have the wiring figured out.
As for the sparking, I tried 2 spare delcos I had lying around and it still sparks. The factory manual has some in-depth info on the delco and it says there is a negligable discharge rate at the across the R2 and R3 resistors. Is this what I'm seeing?; maybe there's nothing wrong. This is the only rig with a delco. The others have motorolas and there is no arcing when the batteries are connected. Thanks

Chris