Tyler Scarabotti

I disconnected the negative wire and tied in a test light between the wire and post. I narrowed the power down to the red wire coming from the battery which feeds the fuse box under the hood. I pulled all the fuses and relays and the light stayed on, meaning I haven't found the problem. Anyone experienced this problem and were able to find what is sucking up the power? I know that wire feeds the fuses, but it must feed all the wires underneath also?

**Update: I also pulled all the fuses from the passenger kick panel and still nothing. I am going to check the fuses under the glove box tomorrow.

dave1123

First of all, why did you tie into the ground cable? You need to tie an ammeter into the positive (+) cable and start pulling fuses. With the ignition off, you should only be drawing less than 1 amp for the radio and PCM memory circuits. I don't recall the actual amperage, but I think it's like 0.17 amps.

Do yourself a favor and disconnect all the wires from the alternator first. A bad diode will keep the field energized all the time.

Tyler Scarabotti

I did the negative because another thread said to try it. I'll do the positive tonight. It's still drawing more than one amp though because it'll drain a battery in a night

dave1123

Well, obviously if it's lighting a test light, you're drawing several amps. Jeep's electrical plan is thus;
There are 2 red wires that come off the positive battery post. One goes to the starter and the other goes to the PDC (fuse/relay box under the hood). A second red wire comes off the PDC and goes to the interior fuse/relay box under the dash, in the passenger kick panel, or behind the glove box, depending on the model and year. If you've got one in the kick panel, there isn't one behind the glove box. ALL circuits in jeeps are fused except the heavy cable to the starter.

As I've said before, disconnect the positive battery cable, then all 3 wires to the alternator. Reconnect the positive battery cable and see if you get a spark when you reconnect it. You shouldn't get anything but a very tiny one from the draw of the memory circuits. Make sure the doors are closed so the dome/courtesy lights are off when you do this.

If you get a good spark, connect an ammeter between the battery cable and the post, then start pulling fuses. A test light isn't going to show you much because it's adding resistance to the system and needs a certain amount of current to light, unless it's an LED. An ammeter will show even the slightest draw.

You should be able to find the culprit when you pull it's fuse. The reason to disconnect the alternator is if it's got a bad diode in the rectifier bridge, it'll keep the field energized when the engine is off.

Good hunting!

Tyler Scarabotti

You're the man! Thanks for all the info and taking the time to type it.

Tyler Scarabotti

I have a .76 amp showing up on the ammeter with the alternator disconnected and with each fuse pulled.

dave1123

The computer and radio memory shouldn't draw more than 0.025 amps (25 milliamps) so you've got something still draining current. If the battery is old, it could be internal leakage of current thru the lead plates. Some older computers will still draw power for about 20 minutes, then go to sleep. IDK if jeep is one of those. 3/4 of an amp isn't much, but it will draw down the battery over time.

If you have that Infinity Gold amplifier under the back seat, pull the plug on that and see if your draw goes down. They have been known to not turn off completely. DISCONNECT THE AMMETER BEFORE YOU OPEN THE DOOR! You can blow the internal fuse in it if it's set on a low range and the dome light comes on.

What was your draw before you started pulling fuses? Which one dropped it the most? We probably should have checked the draw before disconnecting the alternator as well. It's hard to diagnose stuff like this with a keyboard!

Tyler Scarabotti

I started with disconnecting the alternator first so I didn't get a reading. The dome light fuse is currently pulled, I believe the amp is unplugged, and I currently have the drivers door purple and yellow wire unplugged, found out it doesn't work for 96+ zjs and have yet to reinstall it. I will get that plugged in and the dime light fuse and also get a reading with the alternator plugged in.

dave1123

Ya know? I started off trying to be a nice guy and get you started on the right track to figuring this out, BUT this is getting tedious. There are You-tube videos and many posts on several forums that explain this in detail. Please check them out yourself.

Tyler Scarabotti

Easy there killer, you might be a professional at this in life but to me, your a set of fingers typing. I ask questions and people can answer, you don't have to, nor are they only intended to you. Just hit th le back button and forget about it. I'm figuring this out step by step.

dave1123

Okay, so maybe I overreacted, but the way to do this is to start with everything connected, ready to drive away. Then install the ammeter to see what the draw is, making sure everything is off, including the courtesy lights and the underhood work light. On the newer trucks with the SKIM key, even leaving the key in will wake up the BCM.

This reading is what's known as the Ignition Off Draw. The only things that should be drawing power are the radio memory and the PCM memory. This should be only 25 milliamps. If it's more, start pulling fuses noting the draw as each fuse is pulled. Any major drop is a suspect circuit. If there is no drop, reinstall that fuse so you don't have a handful of fuses and not remember where they go. The reason I suggested disconnecting the alternator first is because it's often the cause of the problem and the output wire is not fused except for possibly a fusible link in the wire.

If after pulling all the fuses, there still is a draw, look for corrosion in the wiring anywhere, like under the fuse/relay box under the hood or the interior fuse panel. Again, newer models have an IOD fuse that powers the memory circuits so you can eliminate THAT draw by pulling the fuse. Just remember that killing the memory power will cause you to loose the radio's preset stations and the clock setting, as well as the PCM's fuel trim memory set by your driving style. I have no idea how the alarm system functions so IDK where it gets it's power, probably thru the PCM and BCM.

The only other place to lose power is the battery's internal losses across the plates with debris from them breaking down or acid vapor deposits between the posts on top.

That's about all I've got. Those videos I mentioned may bring up something I missed or am wrong about. I hope this helps and I appologize for loosing it. I am NOT a professional and all my knowledge is from going thru this myself. Peace.