I bought a 98 Jeep Cherokee Sport 2 months ago and in the last couple of weeks the battery kept dying. So I went and bought a new battery becasue it was 4 years old and it needed a new one anyway. That didn't fix the problem. So I checked the voltage across the battery with a Multimeter when it was running and it was at 11 volts so figured it was the alternator. I took it out (by the way 98's are not easy to get the alternator out) and went and got it tested at Autozone and it failed. So I got a new alternator and put it in and nothing went wrong for the last 4 days and then this morning it was dead again. I don't notice anything drawing power when its off. I put the multi on it again today and it seems to be running a little bit low like 13 volts anyone have any ideas or thoughts of what I can do.

 

do you have any aftermarket stero equipment? My father in law had his cb short out kept killing his battery. I would try using your multimeter if it can measure amps disconnect battery take a reading, reconnect battery then take another reading. How long before battery goes dead?

 

is the light going off in your glove box?

 

yeah if you have any kind of amp, check and see if its connected to the remote control wire (no what you think) this wire is what turns your amp off when you turn the radio off. Otherwise, it will just suck power until your battery is dead...happened to a friend of mine

 

I do have an amp which wire is the remote control wire. The positive wire runs to the battery and has its own fuse, the black wire is screwed into the frame and there is this thin blue wire That I can't figure out where it goes. Then obviously it has the speaker wires.

 

that thin blue wire is probably your remote wire. make sure its properly hooked up to you deck. I had a similar problem with the same jeep, turns out it was a combination of many things, but mainly the battery terminal (not the posts) were toast, go buy new ones

 

try this too (if you haven't already)

Disconnect the battery -ve cable from the battery. Connect the ammeter (multimeter) between battery -ve post and the battery cable. It should read .003 amps or less. anything else is current draw from somewhere in your system, zapping your battery. especially since you have the amp remote wire that you've already identified as the possible culprit - you may already have this thing licked.

 

ok if you dont have the remote control wire hooked up then thats your problem, but to be sure, look at your amp when you have the keys out and the jeep off. if its still on then its not hooked up and thats your prob

 

 

The classic way to diagnose this kind of problem is to pull one fuse at a time, checking each time with an ammeter, until the current drain stops. Then at least you know what circuit is involved.

 

I believe Rambler65 is referring to "parasitic draw" testing. There are several good videos on YouTube to guide you through the process, and it is a process.

Happy Jeepin'
TexasTaz38

 

I had the same problem a few years ago. Mine turned out to be the door locks when locked with the remote. I disconnected all of them and no problem since. Some day I will actually fix them.

 

If it's a trusted mechanic, take their word for it and replace the PCM. The voltage regulator is in the PCM and can certainly fail. You can find a rebuilt PCM for a fair price at RockAuto and sometimes on ebay.

If you don't trust the mechanic, charge up your battery and take it to your local parts retailer (Autozone, etc) that does battery and alternator testing on-vehicle and have them run the test - it's free. Have them do both just for the heck of it and that should give you a good idea if your alternator is likely bad. Bear in mind that it could be BOTH the alternator and voltage regulator (so PCM), so you may be looking at replacing both.

Edit - If this is something that occurs --while driving-- it's not a parasitic draw, it's a full blown failure to maintain charge on the battery.

 

Bleepin Jeep has a very good video on parasitic draw and shows you how to find the actual fault, not just what circuit it is.