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Jeep ZJ electric issues #2310057
05/23/17 11:04 PM
05/23/17 11:04 PM
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Pikes Peak Country
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TC@HP2 Offline OP
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1998 Grand Cherokee Limited, got a few issues that may be inter-related but need to tips on trouble shooting.

First issue I noticed was the interior lights would not turn off after shutting down the vehicle. They turn off when its started, return to being on where turned off and stay on after locking the vehicle. Some basic trouble shooting leads me to believe its may be the body module, but could be an issue with the light switch.

To avoid draining the battery while chasing this, I took out all the bulbs. A week later go out to work on it and battery is dead. Charge it back up, install and start checking draw. I find a .4 amp draw on the 50 amp mux/tow circuit which, unfortunately, is the circuit for nearly every power accessory in the darn vehicle. So, I've got something draawing power within some accessory. Also within this circuit are two door control modules, that interface with the body module, which makes me wonder if there is a relationship to this issue and the interior lights.

Looking for Suggestions on ways to continue testing in an effort to isolate without simply replacing parts.

Re: Jeep ZJ electric issues [Re: TC@HP2] #2310346
05/24/17 01:41 PM
05/24/17 01:41 PM
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South Florida
indcontrols Offline
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I am assuming that you have a moonroof - that's where the trouble starts on these - there are holes in the front and back of the moonroof drive channels, the front ones have little hoses that run through the A pillars and down the firewall, the back ones go down and exit behind the taillights...
These little holes and hoses (likely less than 5/16) get clogged up and water seeps down the A pillar and starts affecting the electronics... The cleanout procedure is an air pistol (not at full pressure), and much frustration...
Most every one of these I have encountered has a myriad of different problems, lights, ABS, etc. etc.
If you don't have a moonroof, please disregard .. lol

Re: Jeep ZJ electric issues [Re: TC@HP2] #2310520
05/24/17 06:50 PM
05/24/17 06:50 PM
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Yes, it does have a retractable roof panel. When I picked this one up, the panel was not fully seated. It had plenty of grime in the slides so I wouldn't bet against it having plugged up drain tubes.

So I should look for water damaged components in the a piller and kick panel areas it sounds like. I haven't poked around in these areas, but I know the passenger side has a fuse panel and I assume the driver's side will have a control module of some sort.

Thanks.

Re: Jeep ZJ electric issues [Re: TC@HP2] #2310680
05/25/17 12:12 AM
05/25/17 12:12 AM
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Southeast Pa.
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Also check your A post wiring they tend to break from opening and closing the doors. How are checking for a draw? Are you allowing the modules to go asleep?

Re: Jeep ZJ electric issues [Re: TC@HP2] #2310857
05/25/17 12:08 PM
05/25/17 12:08 PM
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Basic amp draw check on the negative cable while pulling fuses. Started with the fuse block under the hood so all doors were closed and the hood light disconnected

Hadn't thought about allowing modules to go to sleep.

Re: Jeep ZJ electric issues [Re: indcontrols] #2311093
05/25/17 06:43 PM
05/25/17 06:43 PM
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Originally Posted By indcontrols
I am assuming that you have a moonroof - that's where the trouble starts on these - there are holes in the front and back of the moonroof drive channels, the front ones have little hoses that run through the A pillars and down the firewall, the back ones go down and exit behind the taillights...
These little holes and hoses (likely less than 5/16) get clogged up and water seeps down the A pillar and starts affecting the electronics... The cleanout procedure is an air pistol (not at full pressure), and much frustration...
Most every one of these I have encountered has a myriad of different problems, lights, ABS, etc. etc.
If you don't have a moonroof, please disregard .. lol


I had good luck with weedeater string, hope this helps. Modern electrical is crazy complicated when it goes wrong.

Good Luck!

Re: Jeep ZJ electric issues [Re: TC@HP2] #2314314
05/31/17 09:16 PM
05/31/17 09:16 PM
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Balt. Md
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Some of the modules on them can take almost 20 minutes to go to sleep. The Jeeps do have alot of electronics. I worked at a Dodge dealer for many years and would see a Jeep now and then. If you have a scanner and can moniter the body control module as I would as the BCM should automatically turn the interior light out after somewhere from 10 minutes to a half hr even if you left them on so if they stay on it would be good to see what the BCM dome light control is doing. I would want a wire diagrahm on that as with all the modules they have including the door modules it may actually be a different one that controls the interior lights. I cant remember without looking it up and of course they all talk to each other over the Buss circuit which I also dont remember which Bus circuit it uses. It may use the PCI Buss on it but again I would have to look it up. But with a DRBIII you can look at just about every circuit on it. I also had a few that got water in some modules over the years and many times I could open up the module and dry them out and blow them out with air to get them to work again but not every time. I dont think that has the Front Control Module as I cant remember what year we started using them. The normal draw on them after all the modules time out should be 50 milli-amps or less. Good luck , Ron







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