Phoenixart88

So iv been working on my 98 zj for a few weeks getting it road worthy...i just put a Brand new battery in it...and now its completely dead....is there any common places I can check for a short or something? I always make sure no lights or anything stay on but it still dies

dave1123

Fully charge the battery, then put an ampmeter between the positive (+) post and the cable end. If you've drawing more than 2 amps, start pulling fuses until the draw drops. A good thing to check is the alternater. A shorted diode in it will draw down the battery. Actually, disconnect the hot lead to the alternater first. The 2 amps is the draw for the PCM and radio memory.

Phoenixart88

Well I suspect it has something to do with my rear hatch..because I put the new battery in about 3 weeks ago and after the batter I didnt mess with it again for about a week. Went out started it up with np..but i pulled it into my shop getting ready to install some new parts and i was messing around in the back some..closed it up for the night went out the next day...dead as could be..and i did a little research and seen that if the locking mechs are messed up it won't let the bcm go to sleep when it gets closed up there for battery drain

dave1123

It's quite possible the inside lights were still on if the hatch wasn't latched.
You probably didn't look back when you turned the shop lights off either.

Phoenixart88

Well I actually do check for lights...but never see anything...

dave1123

I still think you should do a draw test. A good beginning is when connecting your battery, do you get a spark? You shouldn't. The only things that should be drawing current is the PCM and radio memory.

The alternator produces AC current. There has a diode bridge rectifier in it to convert it to DC. If one of the diodes is shorted, it will still produce DC current, but will cause the windings to stay energized after you shut it off. A good multimeter will show the presence of AC in the output.

Phoenixart88

I actually did notice a spark when I connected my battery.

Willys55

if you did , then that's way more than 2 amps, disconnect the battery and the alternator and then see if you get that spark again

Phoenixart88

So I ran somewhat of a test today...iv been suspecting it was my rear hatch causing the drain so I pulled the panel and unplugged everything (rear window didn't work anyway). But before that I checked to see if I had spark on the battery and sure enough there was a clear arc. Well after I unplugged everything I checked again and there was very little to none. I won't know for sure if that was it or not til I go out today and see if the battery is dead or not. But I think that was the problem.

Phoenixart88

alright so I disconnected all the wires in the back hatch and I left the battery connected overnight (I was just leaving it disconnected) and before it would drain over night but I tried it tonight and the battery started the truck with no problem, so the problem isn't solved yet but it's at least resolved for the time.

dave1123

Try connecting the rear wiper motor and see if you get a spark at the connector. It's my guess this is your drain.

shadowmaker

Any more info on this? My battery has started to drain as well. Battery was bought new in Oct. Dead last monday morning, sitting since Friday, but thought it was bc it was 14* outside. Hard to start this monday but it wasnt dead, threw the charger on it yesterday at lunch. Dead as a hammer today when I went out at lunch.

My latch light on the display up front says the hatch is open even though its not. So, how do I disconnect this? My wiper motor and window is already unhooked.