Prestonj3

I have a white Jeep ZJ with the 5.2 v8 and I'm having trouble diagnosing a problem that draws battery power when the vehicle is off. It is a brand new battery so that isnt the issue. I can plug it to a charger and fire it up and it will run great pushing a little over 14 volts but when i go to start it the next morning I have absolutly no electrical power at all. It doesnt even show dash lights its so dead. If you have any suggestions on what to check please do so!
Thanks, Preston

prcherokee

1998 ZJltd

try the above link ...

I had the same issue with a brand new battery ... after jumping it for 2 weeks and spending hours trying to chase down a parasitic draw .. and returning the battery to PBs twice to have them check it .... I finally got them to believe and understand that their brand new battery that they had sold me and rechareged twice themselves was ...

wait for it ....

Bad ... replaced it and have not had another issue ....

Your results may vary ... you may have a draw ... but don't count the battery out ....

Kingfisher

Charge battery and leave it disconnected overnight.
Connect it next morn. and see if it will crank.
That will tell whether it's a bad battery or a draw.

Prestonj3

So i did the parasitic draw test and I found that my radio was pulling excessive power while my jeep was off. However im still losing battery power while the jeep is off but its just slower. If I leave it sit overnight the battery voltage drops from 12 to below 9 volts. Im not finding any more fixes through doing the test anymore so is there anything that I should check and could it be the PCM sending false messages?

dave1123

Check your alternator for a bad rectifier diode. This will show up as an AC current in the DC output. You'll need a good multimeter to find it. It will cause a current drain when off, but will seem to function properly when running. I found this on 2 vehicles, a Chevy and a Nissan.