93 Jeep Wrangler Parasitic Drain

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71340Duster

71340Duster

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I know it's not an A body, but I can't really work on my Duster until I fix my sons Jeep. He's deployed and I have it at the house, needs to be shipped to Hawaii in a short while.
I'm chasing my tail here on this one, maybe I can't see the forest through the trees. I had the battery tested, two years old, checked good. Alternator is putting out 14.4-14.6. I put a light in line with the positive cable, barely lights the filament so I start removing fuses in the engine compartment, only one that makes the light not light at all is the Ignition 40 amp. I hook up my meter to test current drain and I only have a 70 ma drain, shouldn't that be okay? What's really confusing me is that I have pulled all of the inside vehicle fuses that the 40 amp engine fuse box feeds and I can't find the source of the 70 ma drain. The circuit goes through the ignition switch which I have broken the connection to, still have that drain. What am I missing?
 
Disconnect the alt large wire and see if you still have the drain.
If you don't then there is a bad diode in the alternator causing it.
 
Okay, I haven't done that yet, but did pull the main batt lead into the starter. Thanks I'll let you know what happens.
 
Pulled the alt wire, still have drain but it's dropped to 53 ma. I had trickle charged the battery 2 amp setting overnight to start out fresh troubleshooting, battery voltage was falsely high at 12.77 volts, has now settled down to 12.67, maybe that's why the drain went from 70 to 53. Verified again, removing the 40 amp engine ignition fuse stops the drain completely. I've pulled the starter relay, no change. A couple of weeks ago, I saw this battery get down to 7 volts, I'm starting to wonder if maybe I don't have an intermittent problem.
 
My wiring diagram shows a fuse feeding from the ignition switch for the abs module F13 ? not sure of location ,maybe unplug abs module to be sure, also a circuit breaker feeding the wipers.
Generally anything over .050 draw is a problem.
Here is a wiring diagram.
 

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In normal operation, when the vehicle is turned off there is a delay before all the control modules go into a sleep state. Most vehicles will have only 20-30 ma parasitic draw in a sleep state. Set up your meter and put everything in its original state and let it sit for an hour, then recheck it. If not found in service info there is a formula to determine maximum key-off draw based on battery capacity but I don't remember it.

Ding-dong! Found a reference.

http://www.diagnosticnews.com/parasitic-battery-drains/
 
Here is a good tool and video on parasitic drain, this has a min-max feature that detects a intermittent problem. Expensive tool , but good info on checking.

[ame="https://www.youtube.com/watch?v=YYM3P4vyBtw"]Parasitic Draw Test with the Hook - YouTube[/ame]
 
Thanks all for the suggestions. This Jeep doesn't have ABS but there is a spot in the engine fuse panel for an ABS relay, no relay. I have pulled the wiper 5.3 amp "fuse breaker" I've pulled every fuse that the 40 amp ignition engine fuse feeds, I've also disconnected the parking brake, ignition switch, starter relay, starter, alternator, nothing takes the drain away. It's early evening now and the battery is down to 12.59, I'll see what it's at in the a.m. This jeep is a soft top, no dome light, no wires even go to the door jamb switch. I'll check the glove, don't think there's a bulb in there but if there is I'll see it it's hot when I open the glove box. I don't want to start the jeep, I think it would, I'd like to see how many hours/days it will last on a fresh full trickle charge (I took it off charge at 9 a.m. Friday a.m.)
 
Here's the two schematics I'm looking at. I cut the labels off the pic in one, but the 40 amp in the engine compartment is the ignition fuse, it feeds the starter relay and the ignition switch. I'm stumped but am plowing along. Tomorrow I'm going to a Mopars only car show and swap in Everett WA, will be good to get my mind off of this for a day.
 

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Does it have anything aftermarket added ,stereo ,car alarm, remote start , etc.
Someone could have the feed circuit from your 40 amp fuse in the PDC to the ignition switch feeding something else .
With you still having a draw with the ignition switch unplugged according to the wiring diagram that leaves only the PDC feed circuit to the ignition switch left.

Could the power distribution center itself be a problem, feeding another circuit?

I have felt relays for one that is hot from a feed or relay problem , check in your PDC for that, usually most common thing is someone tampering with the wiring though.
 
blown71duster said:
Does it have anything aftermarket added ,stereo ,car alarm, remote start , etc.
Someone could have the feed circuit from your 40 amp fuse in the PDC to the ignition switch feeding something else .
With you still having a draw with the ignition switch unplugged according to the wiring diagram that leaves only the PDC feed circuit to the ignition switch left.

Could the power distribution center itself be a problem, feeding another circuit?

I have felt relays for one that is hot from a feed or relay problem , check in your PDC for that, usually most common thing is someone tampering with the wiring though.
Click to expand...

It has a stereo and rock crawler lights, I added those and have pulled the fuses. You bring up a good point about tapping into the wiring though, when I pulled all of the interior fuses I put them all back in but the dome light fuse, it's a soft top, no dome light. Anyway, it wouldn't start without that fuse, just cranked . That's a little scary. I'll feel all the relays, that's a great idea.
 
This morning at 0630 battery voltage is at 12.39, I removed the 40 amp ignition fuse, voltage jumped up to 12.40. I'm leaving that fuse out while I enjoy the car show, I'll come back this afternoon and check it. If it's not drained ( and I suspect it won't be), I'll ohm out the ignition switch even though I've pulled it's connector maybe there's a low resistance in there that there shouldn't be. BTW this is a 2.5 cylinder and it's a manual trans, there are some wiring differences and also a 93, so 87-95 wiring diagram (Haynes) is what I have, don't have the factory manual. Thanks again to all who have commented, I'd really like to get this fixed.
 
Heading out, one last check at 0730, it's rebounded to 12.45, a little warmer but not that much
 
Some days you're the hammer, some days the nail. Today was nail. Went to the car show that isn't until tomorrow. Came back, voltage held, put the 40 amp fuse back in and have a 27 ma drain, that should be okay. Started it, shut it down, will see if it drains out again. Intermittent is such a pain.
 
You mentioned forest for the trees. You KNOW what circuit it's on

I assume you are measuring drain current at the main battery lead so as to measure "all" draw?

Keep in the back of your mind "you sure" your multimeter is correct? As much trouble you are having, might be worthwhile to check

Otherwise, it's the painstaking job of checking every single thing on that fuse. I think my first test would be to unplug the engine computer.

Some other thoughts:

How long does this take to kill the battery? 70ma is really not all that much, but IS more that "normal" should be. Some cars seem to drain at about 30ma nowadays..

Was the battery actually load tested? What did this show, IE amp hours, etc?
 
My Dads old New Yorker,that I once worked on, had a digital dash clock. It went to sleep with the key-off. But of course it was still keeping time. It was not on any fuse. The back-liting was on a fuse, but the time-keeper was a continuous battery feed. Or so I thought. It would drain the battery down in a few weeks. Dad couldnt see well enough to drive at night anymore, but kept the car insured in case of emergency. Well he kept coming out to a no-start. I trash-canned the clock. No more issues.
Your results may vary
 
67Dart273 said:
You mentioned forest for the trees. You KNOW what circuit it's on

I assume you are measuring drain current at the main battery lead so as to measure "all" draw?

Keep in the back of your mind "you sure" your multimeter is correct? As much trouble you are having, might be worthwhile to check

Otherwise, it's the painstaking job of checking every single thing on that fuse. I think my first test would be to unplug the engine computer.

Some other thoughts:

How long does this take to kill the battery? 70ma is really not all that much, but IS more that "normal" should be. Some cars seem to drain at about 30ma nowadays..

Was the battery actually load tested? What did this show, IE amp hours, etc?
Click to expand...

The meter is a fluke and it did have a blown 10 amp current fuse in the beginning, I replaced that and the low current fuse checked good plus I have another meter besides the Fluke and they read the same for ma. I am testing between the battery post and disconnected lead, have done both negative and positive. The battery is two years old with 6 months of it's life sitting disconnected while my son was on a deployment, he returned, connected the battery and the Jeep started, he drove it for a couple of weeks with no issues and shipped it out here to WA. I took the battery back to Auto Zone, it's only a Duralast, they charged it all day, load tested it called it good and I don't disagree with that. I believe the battery will last appx 3 days, I've been doing so much fuse pulling troubleshooting, really wasn't putting much effort into it until I got it narrowed down a little. I will unplug the engine computer, I haven't tried that yet, thanks.
 
AJ/FormS said:
If you unplug the computer, all the fuel trims will be lost, and you can expect the engine to idle and run slightly different for quite a few drive cycles.This is normal.It will recover.
Click to expand...

Okay thanks, I guess it will re-learn. It is pretty old (22 years), and it's pretty utilitarian, not a lot of bells and whistles....but enough to kick my butt obviously!!!
 
blown71duster said:
Last resort if you can't figure it out you could put a rv battery disconnect terminal and just unhook if its going to set a while , or they make a disconnect with a switch such as this from Ron Francis:

https://www.ronfrancis.com/prodinfo.asp?number=MS-21
Click to expand...

Thanks for the link, this would be a good band aid but I'm hoping to figure it out. Checked the voltage this morning, it's 12.3. I am going to the car show/swap meet (again), will check it when I get out. I saw a neutral safety switch in the wiring diagram I missed, the truck will start without clutch being engaged so don't know if it's bypassed or faulty? More fun for later.
 
71340Duster said:
Thanks for the link, this would be a good band aid but I'm hoping to figure it out. Checked the voltage this morning, it's 12.3. I am going to the car show/swap meet (again), will check it when I get out. I saw a neutral safety switch in the wiring diagram I missed, the truck will start without clutch being engaged so don't know if it's bypassed or faulty? More fun for later.
Click to expand...
Don't forget to look for any signs of water intrusion or corrosion to the PCM, connectors for same, power distribution panel, etc. Verdigris (green corrosion) is conductive.
 
After a fresh trickle charge I got the ignition engine mounted fuse to show a 70 ma drain again, so started removing interior fuses (again) to no avail. Only removing the 40 amp ignition fuse showed a huge drop in ma drain, so I started again with switches, relays, starter and starter solenoid relay, no joy. I then saw a module I had disconnected prior, but might have not had a fresh charge on during testing, I saw the ma drain go from 53 to just a few ma's. I don't know what this module is. It has six pins and 4 diodes. I looked at the colors of the connecting plug, and can't see anything that looks like it in my Haynes manual, so I'm turning to internet schematics. I'm enclosing a pic, if anyone has an idea of what it is, maybe an ECC? Schematics I have show wires going to an Engine Control Unit, but I can't find the module in the schizmo's, maybe too many beers today ha!
 

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Rustedwrench said:
Don't forget to look for any signs of water intrusion or corrosion to the PCM, connectors for same, power distribution panel, etc. Verdigris (green corrosion) is conductive.
Click to expand...

Thanks, I haven't seen any green, but did have a lot of oil in the engine compartment from a pcv fitting break which could have caused a low resistance from the hot lead to ground or the control lead from the ignition. I cleaned that area up well with carb cleaner and a brush, no help.
 
I remember seeing one of those modules in a car with a Clifford alarm. Can't remember what it did but I think it may have been connected to door switches
 
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