Try pulling relays with the voltmeter hooked up to the battery. You might find it that way. Also, just to double check, have the battery load tested. Most parts stores will do this free and in the parking lot with it in the jeep.

 

I’ve pulled every fuse and every relay and the amperage is constantly around 300 mA. Anywhere else I can go look? Or a different way to test?

 

Have you done the voltage drop test across the fuses? There’s good videos on YouTube


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Have the actual battery tested. I had the same issue and ended up replacing the battery and have not had a problem since.

 

Specifically have the battery load tested.

 

300mA is quite high for a parasitic drain....

Do you have anything connected directly to the battery(not through fuses)?
Audio amplifier not turning off?

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I expect my Jeep has about the same drain with the alarm blinking at me through the window.

Consider this: I have a 70 Amp/Hour battery, right? 70 Amperes for one hour or 70 hours of one Ampere. 70 hours is 2.9 days, give or take an extended coffee break.

This doesn't feel like your core problem. I had a T-Bird back in the day which would do this, too. It utterly baffled me. I'd get a jump, drive it, everything seemed fine and 9 hours later I couldn't start it. Dealer said "It's yer battery" and replaced it. Two days later I needed a jump again.

Get the picture? May not be the battery, but your charging circuit.

I turned on my headlights, including high beams and even with the engine running they were dimmer than they should be. Turned out I had a bad rectifier in the alternator, it charged the battery, but at a trickle, just enough for it to say, "Yup! I have 13 volts!" While the engine was running the alt had enough juice to run all the electronics, with only an actual deficit for the battery with the headlights on. In the discharge curve it was towards the end, where current and voltage drop off precipitously. Have your charging circuit checked. Could be alternator, regulator, or some other electronic gew-gaw between the battery and your alternator (all the electronic junk in cars these days.)

Best of luck!

 

Great suggestion. I was trying to come up with what could happen between the battery and the power distribution center. OP's problem might be before the battery, in the charging system.
Whoda thunk?

The Vikings had a god called Loki. He was in some sense the god of mischief. In today's world, he'd be the god of electricity.

Good Luck, L.M.

 

Auto parts stores will check the alternator for free too. Just take it inside and they can bench test it.

 

Or just Wranglers!

 

Okay, all good suggestions, thanks guys. Heres where I am:

• I’m on my second battery. The parts store tested it yesterday and it tested good. Still might be the battery but I have to get more evidence.
• They tested the alternator, which passed.
• I did find a large voltage drop at the alternator and discovered my main engine ground strap was old and inefficient. Replaced that and charging is definitely better.
• I’m still getting around 250mA draw (amp meter connected between the negative post and main ground line).
• I’ve pulled every single fuse and relay and the draw doesn’t change.
• I’ve disconnected the amp and any other direct connections to the live post of the PDC
• Tested voltage drop over the fuse terminals… nothing obvious.
  
  STUCK!!

 

Okay, all good suggestions, thanks guys. Heres where I am:

• I’m on my second battery. The parts store tested it yesterday and it tested good. Still might be the battery but I have to get more evidence.
• They tested the alternator, which passed.
• I did find a large voltage drop at the alternator and discovered my main engine ground strap was old and inefficient. Replaced that and charging is definitely better.
• I’m still getting around 250mA draw (amp meter connected between the negative post and main ground line).
• I’ve pulled every single fuse and relay and the draw doesn’t change.
• I’ve disconnected the amp and any other direct connections to the live post of the PDC
• Tested voltage drop over the fuse terminals… nothing obvious.
  
  STUCK!!

Let's ask a dumb question...

What do you have installed which is power on 24/7? Alarms of any kind? (Are you first owner?) Is there something else in there which is not factory?

 

Just thinking out loud.... Some alternators have a diode that allows electricity to flow only one way. If the diode is faulty, electricity can flow backwards, like draining the battery with the engine shut off.
You might try disconnecting the wires to the alternator and checking for the parasitic draw then.

Let us know what you find.

Good Luck, L.M.

 

Just thinking out loud.... Some alternators have a diode that allows electricity to flow only one way. If the diode is faulty, electricity can flow backwards, like draining the battery with the engine shut off.
You might try disconnecting the wires to the alternator and checking for the parasitic draw then.

Let us know what you find.

Good Luck, L.M.

LM, good to hear form you again! Yeah, I just learned about the diode thing last night so I'm going to disconnect that this afternoon and see if that does anything. I'll definitely let you know.

 

Son of a... okay, the alternator diode test was good so it's not that either. Now I'm really stuck. Could it be a bad ground? A shorted 12v feed somewhere? I can't figure out why pulling the main fuses & relays in the PCD didn't do anything.

 

Inspect for rodent damage? I've had a visitor under my hood, batting and foam ripped up. So far no sign of electrical damage. Touch wood.

 

Your (+) battery cable probably goes to a Power Distribution Center (PDC) under the hood. I'd disconnect the (+) cable at the battery and connect the digital multimeter between the battery and the cable end. Then I'd start disconnecting wires one by one in the PDC and watch the multimeter. When the draw drops to "0", you've found the pathway to the problem.
Disconnect one wire, watch the meter. Reconnect the first wire and disconnect the second wire, (or fuse, or relay or whatever in the PDC). When the draw stops, follow the wire to the problem.
Look for a post by Got it at last, IRQ or gat. Each of those members have links in their signatures to several Factory Service Manuals. Click on any one of the links and then click on the FSM that fits your year Jeep. The schematics are likely in the Electrical Troubleshooting section.

Here's a link to some info on parasitic draws. One suggestion is to use a solar charger with enough power to overcome the 250-300 mA draw. I see that as a last resort. I'd rather search out the cause and repair it. I keep everything that I don't use daily on a battery tender.

What is "Normal" for Parasitic Draw?

www.optimabatteries.com

Let us know what you find by disconnecting the various circuits.

Good Luck, L.M.

 

Man, I'm totally stumped. Took everything off one by one and nothing reduces the 250mA draw. I think I'm going to take it in to my mechanic. HATE that!

 

I don't want to sound argumentative, but I'm pretty sure if you disconnected all of the circuits, one by one, the draw would have stopped when you disconnected the guilty one. My '87 doesn't have a PDC, so I'm unfamiliar with just how the PDC is set up. If you post a pic, perhaps one of us can offer more suggestions. I'd hate to take the jeep to a mechanic too, and pay $100.00 per hr. for him to fiddle and snoop without any guarantee that he can find the problem.

Have you checked the schematics in the FSM for your year Wrangler to see what circuits go into and out of the PDC or the fusebox? Perhaps the problem is in the fusebox. What happens when you unplug the plug on the firewall near the brake booster? At least that way you'll know if the problem is under the hood or under the dash.

Keep us posted.

Good Luck, L.M.

 

I agree with LM, stay at it. Don’t let it defeat you + the reward is better.


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Okay, guys, I’m very embarrassed to admit that I think I’ve been chasing my tail here. I’ve had the positive lead connected to the battery terminal where it looks like it should be the other way around. With the leads connected with red to the neg lead and black to the battery post I’m now showing 20mA. Why the number was higher in the other direction I don’t know!!

Still don’t know why the battery is dead in the morning but I think I’m at least measuring the draw correctly now!! IDIOT!!

 

In post #19, I suggested connecting your multi-meter between the (+) terminal and the cable end. Maybe we both learned something.

Does any automotive electrical expert have any information to offer on jhendry's situation?

Good Luck, L.M.

 

Okay, finally got a break in the rain and cold and went out to have another look at this. I've attached a couple of photos. The battery continues to drain while it's sitting in the driveway. When I disconnect the neg at the battery and put the ammeter between the neg battery post and neg cable I get a consistent .019A. I've had it connected for a couple of hours and it never spikes. That seems good, right?? Obviously the battery stops draining when it's disconnected and only got the ammeter connecting it. I tried to turn on the ignition and don't get any additional draw. Any auto electrical guys out there to help us out?

 

Auto electrical is black magic…

1. Connect the ammeter between the neg cable and neg battery post.
2. Pull all fuses one at a time. No reduction.
3. Do this over and over and over proving hoping a for a different result and proving my insanity.
4. Happened to see a test light lying in a drawer and connected it alongside the ammeter.
5. Found ONE circuit that when I pull the fuse caused the light to out (and, only when the test light is connected, the ammeter goes down to zero).

It’s black magic.

 

Auto electrical is black magic…

1. Connect the ammeter between the neg cable and neg battery post.
2. Pull all fuses one at a time. No reduction.
3. Do this over and over and over proving hoping a for a different result and proving my insanity.
4. Happened to see a test light lying in a drawer and connected it alongside the ammeter.
5. Found ONE circuit that when I pull the fuse caused the light to out (and, only when the test light is connected, the ammeter goes down to zero).

It’s black magic.

Seriously... you're gonna leave us hanging like that?

 

I wish I could help. Maybe call a priest?

What circuit does the thing with the test light happen in? That might be a clue. The test light bulb may be absorbing the the amount of parasitic draw. Is the test light bulb bright or dim?

1- Apparently the fault is in a non-fused circuit. Have you studied the schematics in the FSM? I'd look for a circuit that isn't fused or perhaps for a section of a circuit between the battery and a fuse.
2- Have you disconnected the plug on the firewall near the booster to isolate the passenger compartment from the engine compartment? If so, what happens?
3- My '87 has fusible links on the starter solenoid. If you have the same thing, have you disconnected them? If you have fusible links, your '94 may have them on the starter relay. You may not have a solenoid like my '87.

Good Luck, L.M.

 

Which one!?! We can't wait

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Sorry guys!! Went away for the week but I'm back now. I'm going to get back to finishing this off this weekend. I've spent MANY hours before in the FSM but it won't help here because I think I have used the ASD circuit for something else (remember, I have a Ford 302 so the ECU doesn't use the ASD circuit). I think, now that I've found the circuit, I just have to figure out what I've used that circuit for in all the rewiring I did. I'll definitely update once I'm 100% sure.

Still not sure why the test light worked but there's so little amperage drop without it but I know it's the one because when I pulled that fuse for a night the car started right up next morning.

 

What doesn't work when you pull "that" fuse and have the Jeep running?

Good Luck, L.M.

 

Well here we are. I found it. When I was wiring the Jeep PDC to the Ford engine i needed a 12v supply for the VPWR circuit on the ECM. I found that 12v at the ASD in the Jeep PDC. When I cut that circuit today the draw stopped. I’m still trying to find the Ford wiring diagram to confirm it but I found some information online that suggests that the VPWR circuit should be fed by an ignition 12v (start and run only), which makes perfect sense. So tomorrow I’ll give the VPWR a ignition only feed and the problem will be solved.

Thanks for hanging in with me through this guys!!