Battery drain
 

I have a 72 GMC Sierra Grande. Has new battery and Alt. Battery drains overnight. Any ideas? :gmc: :flag:

Look in the FAQ section I think there is a guide to finding a key off drain. Essentially you can connect an AMP meter on the battery cable and start pulling fuses till your amp meter reads zero.

Thanks Walker

Does your horn work? The first place I look is the horn relay. If your horn works you get to look elsewhere.

I like to use a 12V test light to check for a draw. Same principle as the amp meter. Pull the fuse and put the ground to one side of the fuse block and the pointy part that you usually jab into your finger when testing a wire to the other. If there is something shorted in that circuit it will light up. That will at least narrow it down some.

I have to agree with da-burb on the horn...either that or a messed up alt. They can cause drain too.

LOL

Ah yes that end.

I used a test light on each fuse separately. It lit up on all of them. The horn works. I removed the pos cable and the motor still runs. Any more ideas?

Check out THIS post, it'll give you a step by step procedure.
Sounds like you just probed the fuses...this means all your circuits are good.
By removing the battery cable with the engine running, you verified that the alt charges at 2 or so amps.

Longhorn Man,
Thats how I checked the circuits, from the post you left a link of. All circuits lit up test light.

lol .... tossing da-burb a bandaid

If you have checked each circuit?, With every thing turned off "unhook" the pos+ terminal from the battery and place a test light in series(one side to the battery and the other to the pos+ wire) the light should not light up if everything is ok. You may have diods in the alt. bleeding or like I had one time a under hood light on a pontiac that was staying on.
Just go though the wiring one by one un hooking components till the light goes out.

Hmm, try unplugging the ignition switch as you do the test.
I wonder if it is stuck in the ignition position or something.
You stated that the engine continues to run after disconnecting the battery, have you had problems with it not shutting off? Do the wipers work when the key is in the off position?

thanks I will try that