Random dead battery/Won't start
 

Hey folks, first post for me here and looking for thoughts on an intermittant issue with my old race biek hauler

The beast:
2000 Blazer LT 4wd 4 door
Every option chevy put in the thing including the heavy duty trailering wiring kit

Here's the problem - if i don't run it every day (and sometimes even if I do) the battery is getting drained, and I mean dead kind of drained. I'm currently in the process of replacing the positive lead to the battery as it's the only thing I can think of that might be causing issues - it's fairly scarred from corrosion, patched it a while back for a bit usinf a good hot water cleaning wire brush and dielectric grease, not sure that's the issue tho as the battery after sitting in the truck for a week without the engine running was so flat it took a decent charger about 24 hours to recover it - so I'm thinking I have a drain to ground somewhere in the harness - thing is I don't really know where to start looking - the beast does have teh auto diming mirrors - driver side popped the lead to the glass years ago tho, hasn't really ever been an issue. starter has been replaced once a while back - no issues to report there, have to figure out why the heater doesn't work in the winter - might that have somethign to do with it and if so what?

Any thoughts or possibilities would be greatly appreciated.

I doubt replacing the cable is going to fix the problem. It sounds more like you have a grounded wire somewhere else in the truck or a component that is not powering down. You'll likely have to go through the fuse box and determine which circuit is staying powered up.

Ya I was afraid of that, was hoping someone here might have had a similar expeirence and maybe a good place to start

I know there is a tool that looks alittle like a screwdriver that you can just press onto the fuses. If the fuses in the fuse box have an indented metal contact, you can use that tool to find continued power through a circuit. I may be wrong but did see it in action once.

This link has a bit more knowledgeable info to check it without this particular tool.

https://blazerforum.com/forum/2nd-generation-s-series-1995-2005-tech-41/2000-s-10-blazer-wiring-problems-19329/

Hope this helps. Wiring issues are rough. You really have to be committed and go through each circuit to troubleshoot effectively.

i have a 97 blazer and i replaced the trailer light harness and i had that problem rewired it now waiting to see if it was the problem. also have you have a remote start put in, that can sometimes be that case. there was one on my blazer when i got it and it killed the battery and ignition switch

Update - hooked the meter up in series with the negative terminal tonight, had a half amp draw continuous. Started pulling fuses under the hood, TBC 10 am fuse dropped it to .007 amps - I have the shop manuals so I looked up the bit, Body Control Module, so I plugged the fuse back in and started on the in cab fuses, guess what, dropped to 100 milliamps when the courtesy lap fuse was pulled from 400 milliamps. I have a hunch I might have a faulty door switch which just might be keeping the control module in wake up mode constantly as it's one of the triggers (then again I'm not sure which light it's running....)

left the fuse out and the fully charged battery in the truck, will report back in a couple days and see if the beast starts.

Please keep us updated. I have the exact same truck, with the same features, and the same problem. I can go out in the morning and find a dead battery, randomly, never know when it will happen. I replaced the alternator, idler, and tensioner. It charges at 14.5 volts, but the voltage is slow to climb up when started, not sure if this is normal either. Once started in the morning it has never given me an issue the rest of the day, only overnight and very random.

Thank you

Jon

Update for you all - the courtesy light fuse is presently out of the inside fuse panel and things have been fine on the truck so far. So here's what I did - hooked the dmm up in series on the 10 amp setting on the negative battery post to negative cable and started pulling fuses with the key out of the ignition, draw was .5 amps continuous with all the fuses in place. Got to the 10 amp fuse that runs the Body control module and the current draw dropped to .007amps - put it back in and went to the internal fuse panel, when the courtesy lamp fuse was pulled the draw went from .5 amps to .1 amps, additionally I noticed the coutesy lights didn't turn off after 5 min with the driver side door switch depressed - I think in the end I have a faulty door switch and the body control module isn't going to sleep and draining the battery.

One suggestion for ya deadog - check the positive cable for corrosion or buildup (if buildup dip it in screamin hot water to clean it) then use a bit of dielectric grease (vaseline works in a pinch) and see if the random no start goes away.

I also replaced the idler arm, and the alternator when i encountered this problem.. But it did not fix it.. there are still times when it wont start..

Well 2 weeks have gone by with no repeat of the issue I think I have my culprit

dieletric grease on the positive terminal at the battery and use a multi meter on the 10 amp side inline with the negative battery post to ground and start pulling fuses - meter should read .070 ish

one other thing to check - make sure the other end of the ground is clean and tight