Difficult Electrical "Phantom" Shorting Issue on 98 Cherokee

So approximately every year the battery dies even though alternator checks out fine, and my initial investigation with my multimeter turns up the following, which to me means there must be a shorting issue:

With battery out of vehicle, the continuity tester shows brief continuity ( for about 4 or 5 seconds) between positive terminal and negative terminal or chassis ground (either way) then fades away. Then if I test again in a minute or two the same thing happens. :eyes:

Though due to the fadeaway rather than constant reading, I wonder if this could be due to some capacitor or relay thing (as continuity testing puts a small voltage across). Like it builds up and then discharges, but still this shouldn't happen across the positive terminal to ground should it?
I'm trying to relate this finding with the slow battery death, but I don't know how to proceed !!!1
It's not the best conditions for just poking around (26 degrees and windy with no garage) so can anyone give me some ideas about how to diagnose this?
All the usual suspects (dome lights, glove lights, worn insulation etc have been ruled out in any case)

Thanks,
Bruce

Is it happening at around the same time each year? What kind of battery are you using? Oh yea and the usual questions, year, engine, trans etc.....


Your saying that the alternator is testing good. How are you testing it? Just because your seeing 13v or more doesn't really mean its making enough amperage to feed all the things in the Jeep.

You could also try taking your meter with it set to AC voltage and with the jeep running test across the battery terminals. If your seeing AC voltage you have a bad diode in the alternator. AC voltage will cause a slow death of a battery depending what the readings are.

Hey Bro, thanks ideas!

Sorry, 98 Cherokee Sport 4.0L 4WD....

I know the alternator is good because I took it out out and had it tested at Autozone and yes I know they are a bunch of bumblers arty: but the tester they have seems OK.
Slap me if I'm wrong, but there shouldn't be any continuity across the positive to negative or ground in any case should there?

I'll go jump it and see what happens with it running and report back>
thermals, check. glove liners, check. torpedo heater pointed at front of jeep,check. Here I go
Bruce

wheeling365 said:

Is it happening at around the same time each year?
You could also try taking your meter with it set to AC voltage and with the jeep running test across the battery terminals. If your seeing AC voltage you have a bad diode in the alternator. AC voltage will cause a slow death of a battery depending what the readings are.

Click to expand...

No AC voltage across terminals, 14v DC across them. The battery does not go at any particular time of year.
What about that 5-second short across the terminals when battery is out?

All you are reading is the PCM and radio memories being drained.

As asked--what brand of batteries are you buying? What size? How many CCA?

How have you tested for parasitic draws?

What electrical add-on items do you have--XBox 360, 30" flat-screen HDTV with Dish Network DVR?

So Joe....

Hey Joe,
The batteries I buy are usually the Everstarts 880 CCA but it varies....

As far as ad-ons go, my revolving satellite dish attached to the roof, and the HDTV screen in the back cargo space are powered by the windmill on the front grill, when I need more juice I just head into the wind.:cheers:
(no add-ons actually, just an aftermarket stereo but this problem pre-dates that anyhow, though the radio IS static prone which sometime indicates a bad diode I've heard... ANYHOW.....)

Here's what's happened so far:
I've tested for draws by disconnecting the negative terminal and hooking a voltmeter between the terminal and battery post and it reads a 12 volt draw iratefla!!!!!!!!!!!!
And with the voltmeter in place like that, I have systematically pulled one by one each fuse out of the PCM and found that when a combination of two of the mini-fuses near the center of the PCM are pulled, the drain disappears. Da dunt da da :music:

Someone told me you should use an analog type meter for this rather than a digital like I have, not sure why they said that...

BUT, these nine mini-fuses are not labeled anywhere in the owner's manual, Haynes or Chilton so I can't nail it down! :flamemad: Any suggestions?

I'm a bit rusty with this but if your measuring the voltage draw thru the negative terminal your going to see 12v if anything draws any power. You shoud be measuring amps that way. Ideally close all the doors with the key off and disconnect the under hood light. You should see a very low amp draw. I can't recall what readings your looking for anymore.

As Joe said the only things that draw power constantly should be the radio memory and the ecm.

http://naxja.org/forum/showthread.php?t=76389&highlight=power+distribution+center

read through this thread..it has fuse info and pictures farther along in the thread

wheeling365 said:

I'm a bit rusty with this but if your measuring the voltage draw thru the negative terminal your going to see 12v if anything draws any power. You shoud be measuring amps that way. Ideally close all the doors with the key off and disconnect the under hood light. You should see a very low amp draw. I can't recall what readings your looking for anymore.

As Joe said the only things that draw power constantly should be the radio memory and the ecm.

Click to expand...

I believe the most you should see is 3 or 4 volts from radio or ecm so the 12 volt draw means something is wrong I am pretty sure>

McQue said:

http://naxja.org/forum/showthread.php?t=76389&highlight=power+distribution+center

read through this thread..it has fuse info and pictures farther along in the thread

Click to expand...

Thanks Mcque, checking it out now, I think if I get a diagram indicating what each minifuse is I may be able to nail it down..... hopefully!

Hey Mcque....

Would your understanding be the same as mine on those minifuses?

16, 17 and 18 locations are spelled out, but 21 and 24 are omitted so a diagram would look like this (bottom of screen being the front of the jeep):

(26) (22) (18)
(25) (20) (17)
(23) (19) (16)

Is that the layout? Someone in that other string had a diagram but it seems to have too many fuses, there are only 9 of 'em.

There should be 12 mini fuse slots in the PDC, even if you don't have fuses in all of them.
Here's some junk on the PDC and cabin fuse layouts. I don't have the lists for 00/01, but you should be able to find those around here. The rest is from my 97 owner's manual- it may not be exactly what you have, but one or the other should be fairly close.

http://i266.photobucket.com/albums/ii244/AHhub/forum stuff/2001PDC.jpg
http://i266.photobucket.com/albums/ii244/AHhub/forum stuff/DSCF5572.jpg
http://i266.photobucket.com/albums/ii244/AHhub/forum stuff/DSCF5570.jpg
http://i266.photobucket.com/albums/ii244/AHhub/forum stuff/2000_fuse_box.jpg
http://i266.photobucket.com/albums/ii244/AHhub/forum stuff/DSCF5573.jpg
http://i266.photobucket.com/albums/ii244/AHhub/forum stuff/DSCF5574.jpg

Curious about something- when you say the battery dies every year, do you mean it completely fails and has to be replaced, or is it just completely drained and has to be recharged?

Hey Hubs,
The battery drains several time a year and eventually I think due to the excessive draining it eventually completely fails...

I think my findings with the voltmeter are indicative of a real issue. I wasn't measuring amps but I don't believe there should be a drop with the key out and my meter set across as described earlier and as I have said, the drop dissappears when two of these fuses are pulled....

It's just that on my '98 (and I have the manual) these 12 slots (nine of which are used are not in any diagram...:confused1

HOPING JOE PETERS CAN STOP IN AGAIN

12V key off isn't a problem by itself. What sort of current draw are you seeing?

VOLTS is VOLTS. Hooking up a voltmeter in series will show you available battery voltage--DON'T MEAN A THING.

What we need to know when looking for parasitic draws is how many AMPS are being pulled.

OK--OLD SCHOOL is to put a 12 volt test light in series with the the battery and negative cable clamp. What happens is if the lamp barely glows OR doesn't light up at all, then there is either an acceptable minimal parasitic draw OR no draw at all. Now, if the 12 volt test light lights up BRIGHT, then the parasitic draw is excessive and needs to be found and resolved. This is when the brilliant part of using a light shows up--while observing the light you start pulling fuses until the light goes out--that circuit has the draw. You can accomplish the same thing using any multimeter that has an AMPS circuit, HOWEVER, each time you pull a fuse you have to jump up and run around to look at the meter display.

Again, for those that were texting and chewing gum at the beginning of the lecture--volts is volts, we don't care about the volts. Measure the AMPS.

NORMAL parasitic draws in modern vehicles should be less than 50 milliamps, better around 35, and most XJs run around 28.

Good article on parasitic draws: http://www.wikihow.com/Find-a-Parasitic-Battery-Drain

OK I am seeing the light after reading that Wiki and remembering things I haven't remembered since getting married....

Joe my meter is the digital type Greenlee CMT-60 with a clamp for measuring AC amps, I don't think I can use it in this situation,the clamp is for AC amps and when I connect the pointed leads and put it in amp mode it doesn't do anything. So is that why someone said to use an analog meter?:bawl:
Tomorrow I will try the lamp method or an analog meter is that right Joe?

I really need to know what those nine minifuses go to though.


BTW, how do you put photos up on here?

And THANK YOU my JEEP BROTHERS:wave1:

Ok, you need a photo host sight to upload the pictures--like photobucket.com, then just copy the IMG location and post that on .

EDIT: had to search on your meter. Unfortunately, it doesn't do DC current (Amps). A meter like this from HF:http://www.harborfreight.com/ac-dc-digital-multimeter-37772.html has the DC current (Amps) function, the yellow connector and on this meter 20 amps DC is max.