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95zjOrvis 03-10-2013 05:12 PM

Battery dead again, parasitic drain?
Hi everyone,

I hope someone can help me since this is driving me crazy. I bought a 1995 Grand Cherokee Orvis on craigslist last fall and it was awesome all through winter. However, recently it has been having issues where the battery fully discharges. If I leave it for more than a day without driving it, it will usually die.

I replaced the battery a month ago, and it gave me no problems until I let it sit Friday, tried to start it Saturday and the battery was so drained the interior lights wouldn't come on.

After doing a bunch of research on google, the best I can come up with is I think the battery has a parasitic drain. Usually I daily drive it so I figure charging it while driving was offsetting the drain.

I have tried disconnecting the negative battery terminal from the battery, running my ammeter in series and it shows a drain of about 580mA. This is with all doors closed, lights off, hood light unplugged.

I spent time individually unplugging all the fuses in the power control module under the hood. The only fuse that changed the current was #16, the IOD fuse. I know the IOD fuse is supposed to have a small amount of current running through it (I've heard ~30mA), but when I pull that fuse it drops the full 580mA to about zero. If I remove the fuse and measure the current through the fuse socket it is also about 580mA.

To me, this says I have a parasitic drain somehow related to that fuse. I can't seem to find a wiring diagram and I have no idea what to check next. Any thoughts?:confused:

spidermonkey 03-10-2013 06:25 PM

When I was hunting one down I did the same thing but I pulled the fuses in the kick panel. Try that perhaps?

Montaska 03-10-2013 06:49 PM

This post may help you:

I had a similar problem and turned out I needed new battery cables. It could be a lot of different things, I wish you luck!

dusterdude 03-10-2013 08:29 PM

I had a brief issue with my blower motor running all the time

Candymancan 03-11-2013 12:54 AM

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You arent turning your key too far toward you when you turn it off are you ? That leaves the radio on and can drain the battery... My moms BF always freakin does this when he borrows her 4.0.. I always have to go and check to make sure he didnt do it again.. No matter how many times i tell him lol

Scopez 03-11-2013 07:20 AM


Originally Posted by Candymancan (Post 15113455)
You arent turning your key too far toward you when you turn it off are you ? That leaves the radio on and can drain the battery... My moms BF always freakin does this when he borrows her 4.0.. I always have to go and check to make sure he didnt do it again.. No matter how many times i tell him lol

+1 I can do that in my ram 1500, gotta check everytime.

95zjOrvis 03-11-2013 08:05 PM

Thanks for the replies. So far:

I have tried all the fuses in the kick panel, none of them made any difference to the current being drawn.

I don't think I am leaving the radio on. It's never playing when I take the key out, and the lights go off, so I assume that's not the case. Or, will it turn off but still draw excess power when the ignition is off but leaning toward accessory, without lights being on? I can't remove the key when the ignition is set to acc. It seems that the drain is sporadic though, so if this is the case it would totally explain why the drain is sporadic.

I've heard a bad PCM can make crazy things happen. Sometimes my rear defrost turns on for no reason. Also, my alternator typically charges my battery in the 14.8v range - this seems a little high right? I was worried my battery was just being destroyed due to overcharging and that's why it wouldn't hold a charge overnight; after replacing the battery it gave me no issues for about a month, but I did daily drive it. Anyway, could a bad PCM be pulling current when the ignition is off? If anyone knows what systems are actually connected to the IOD fuse that would be really helpful, then I could start trying to test those systems individually.

For the time being, I'm just pulling the IOD fuse every night. I want to avoid wiring in a switch to that circuit if I can help it.

JS97ZJ 03-12-2013 03:36 PM

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Here's the diagram for the 93-95
Check the amp wiring under the rear passenger seat. The whole wiring diagram is much too large to post.
Let me know if you need more.

95zjOrvis 03-12-2013 04:40 PM

Wow, you rock! I will spend some time with this and see what I come up with.:2thumbsup:

95zjOrvis 03-12-2013 07:20 PM

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Ok, here goes. Disclaimer: I have never tried to read a wiring diagram like this before, please forgive me if I ask any stupid questions.

JS97ZJ: First off, I took your advice and checked the amplifier under the rear seat. I checked every wiring harness by the amplifier, disconnecting each one and keeping an eye on the current being pulled. No change in current from disconnecting any of the harnesses, so I assume they are not related to the drain.

I spent time trying to understand the diagrams you posted. The fuses listed in the diagrams (such as F1, F14, F11, etc) don't have numbers that match the labeling in the owners manual, however I believe I figured out the numbering convention in the diagrams you posted. I believe that fuse F1 is the IOD fuse (#16 in the owners manual), due to the fact the amp ratings match up, as well as the fact that pulling F14 kills power to F1. That's what I would expect based on the diagram, so if I'm wrong please let me know because I'm reading this all wrong.

My next steps were to pull fuses 5,6,7,8 and see if they had any effect on the current. 5,6, and 7 had no effect. Pulling fuse 8 increased the current from 560mA to about 600mA. I have no idea why, doesn't make sense to me, but that's what the meter reads. (Side note, I've been doing testing with fuses 6 and 7 removed to avoid constant interruption from the alarm relay and flashing lights, and to avoid blowing my multimeter fuse. I have done the same tests with all the fuses in and it made no difference to the draw when the alarm was shut off)

If I am reading the diagram right, I assume the problem must reside between fuse F1 and the boxed grouping labeled Fuse #6 (that also contains 5,7,8), due to the fact pulling 5,6,7, and 8 didn't decrease the current draw. I have circled this area in red. This is where I get confused, as I'm not experienced with these diagrams.

What does the symbol ---> >--- mean? Is it a connector? In the diagram, the box labeled F8 Inst Panel sits next to this symbol. Does it mean that the instrument panel is connected at that point? Again, I apologize as I have very little familiarity with these diagrams. Hopefully my logic has been sound up to this point.

Thanks in advance for the help. I love this Jeep, most awesome vehicle I've ever owned despite having 190k on it.

Candymancan 03-12-2013 08:02 PM

193 Attachment(s)
those diagrams always confuse me lol

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