93 GMC battery drain

[speed]

I have a 93 GMC Sierra that Im trying to track down a battery drain issue, if you let it sit for about a week the battery goes down to a low 12 volts, enough the dome lights come on but the starter just clicks.
I checked the alt with it running it was putting out 14.8-14.9V, unhooked the battery and checked at the battery terminals with an ohm meter there was a .003 ohm draw. Pulled each fuse until I got to the courtesy light fuse, pulled that fuse the draw was gone.
Is there any certain part on this circuit that commonly goes bad? Does anybody have a wiring diagram for this circuit? This truck is 99% original, it still has the original radio and tape deck.
TIA

[speedygonzales]

Does your courtesy light function correctly?

[speed]

The lights under the dash do not light, I'm not sure if there is any bulbs in them or not. Dome light works properly.

[dragginmetal]

Originally Posted by speed

Is there any certain part on this circuit that commonly goes bad? Does anybody have a wiring diagram for this circuit? This truck is 99% original, it still has the original radio and tape deck.
TIA

Wiring diagrams post #5.
http://67-72chevytrucks.com/vboard/s...d.php?t=445487
I seem to remember reading something a bought the radio or the amp being a problem. I searched around some, but couldn't find the thread. I was thinking it was here, but it might have been on a different site.

[speed]

Thanks for the diagrams. It could very well be the radio there has been at least 1 time in the past when the radio didn't work right that I'm aware of. The truck was my dads and he had it since 94.
Also I see the cigarette lighter is on the same ciruit, those were commonly known to go bad on other GM models and cause issues.

[speedygonzales]

Your not going about finding a draw the correct way. If there is a draw at all. I doubt you have a stray draw on the battery. This past summer I had the same issue that turned out to be the battery. Unless you just bought the battery, it should be electronically tested. Not simply load tested.

Second, you want to use a meter that will read current. But you have to have a good meter that does NOT have a blown fuse. The ammeter is put in series between one of the battery cables and the battery terminal. The problem with a bad meter is if you are looking for no current draw, a bad meter will show you NO current every time. LOL

A reasonable draw on the battery with everything off is .02 amps. Above that will give you issues. The higher above that, the faster the battery goes dead.

Let us know what you find

[speed]

Ive tried 2 different battery's, that was my first thought also, both drained down in about a weeks time so there is deff a draw somewhere. It has been load tested on the original battery that was OK, I don't think there is anybody local to me that can electronically test a battery.
Im using my Fluke digital multimeter checking the resistance on each circuit by pulling each fuse until there is no resistance, with the meter connected at the battery leads disconnected at the battery of course. This is just to find which circuit that would be at fault though. Too cold last couple of days to do much more.
Ill be working on it some more tomorrow and if I come up with an answer Ill post it up.

[83GMCK2500]

I chased a massive draw on my friend's Jeep this summer; with my DMM on DCA I disconnected the negative cable, wedged the positive probe in the cable and held the negative cable on the negative battery post. (Note for others, technically probe direction doesn't matter when measuring amps, it's still gonna measure the correct magnitude of draw it just may read as (-), swapping the probes yields a (+) reading of the same magnitude. Most important thing is amps or current draw has to be measured in series, as mentioned previously; or with an Amp clamp.) I had another friend at the fuse box going down each row pulling the fuses. When we finished underhood we went inside, tracked it down to aftermarket stereo, CB, and factory dome/interior lighting. With the Jeep's unibody I have a feeling grounds are a big issue. I know GM likes to skinch on grounds so check them very well. You '93 will likely have: battery to body, battery to frame, battery to engine, frame to body, body to engine. A clump of them are on the back of the passenger side head to the body near the heater core and down to the frame. Highly recommend at least cleaning and checking condition of them, if not upgrading/replacing them. I think we have a vendor here who sells a kit for it if you're interested.

[speed]

Thanks, I will check those also, I'm sure they have never been cleaned.

[speed]

OK I think I have found most if not all the problem. The underdash lights don't come on at all, one bulb is blown the other is OK. The sockets have full voltage regardless if the door jamb switch is pushed in or not. Also the passenger side door jamb switch does not turn on the dome light when the door is opened until you "wiggle" the switch then the dome light comes on.

[83GMCK2500]

Awesome. Keep us updated please, always great to see a problem solved.

[speed]

Will do. Also looked at the ground wires and I am cleaning those up also along with replacing the original neg battery cable for good measure.

[83GMCK2500]

Good call. We can be as meticulous as possible but cable insulation will break down and oxidation/corrosion will set in. I have some real good pics saved somewhere that I will try to upload later for future reference. It is my hope that others will seem them and take a close look at theirs. Might save them some trouble/money/frustration in the long run.