jedijeb

I have an 85 XJ with 2.5L. The battery has been going flat within a week or so. I can jump it and it will charge up and you can start it the next day, but wait a week and it will only click, two weeks and not even the gauges will work. Had the battery charged (only had 5v left in it, 0 cca) and tested and it tested out fine at 550cca.

Every time I hook it up I do hear a relay right in front of the battery click. It is a metal cased relay, not sure what it is for. The only thing pulling current should be the digital clock. Anyone have any ideas where to start looking for a constant draw when the key is off?

TransAm79

I always start with grounds. Are all your grounds good? Are cables nice and clean and fresh?

Pull your headlights on and have a friend start it. Do they dim and almost go out when you try and start it?

RTorrez1

After checking all of your grounds and if you still have the same problem check out the link I attached. Also you should have a load test done on the battery to make sure that it's not going bad.

jedijeb

Had the load test done, said it was a good battery.

A bad ground should not drain the battery when the key is off, if anything if it wasn't grounded it should drain less. I know it would not charge well for sure with a bad ground but this is loosing charge while it just sits. Seems like something is either shorted or still active when the key is off.

Does anyone know what the relay right next to the battery might be for that clicks as soon as the battery is connected?

That video was very informative, I need to see if the meter I have has amps or just volts and ohms, I can't remember right now.

jedijeb

Ok, followed the video and found a 70mA draw, not much more than what it says is normal draw of 50mA. Turned out to be the Tach I installed, had it tied to a live fuse instead of one that came on with the ignition. Have the draw down to about 7mA now.

That battery that Advanced said was good, not so sure. Put it back into the Jeep and tried to start it, turned it over a few seconds no response. Pumped the pedal a couple times and tried again, few seconds nothing. After the fourth time starter started to drag and dash volt meter was reading about 8 volts. Checked it with the meter and it said 11v. Hooked up the jumper cables from my pickup, with it running as soon as I hooked them up could hear the draw on the engine as it pulled on the alternator. Little later and I could turn it over ok, but after a few tries volts on dash drop and starter drags, let it sit a few minutes and good to go again. I think there is definitely something wrong with that battery.

No start, that is new now. After several tries I pulled a plug and found no spark at all. pulled the coil wire and tried it on a ground and no spark. Coil is getting warm so it is getting current, and the ignition box is getting warm also so it is getting current too. Now I am wondering if maybe it is a bad ignition box or maybe bad pickup coil in the distributor. Is there any way to check the pickup coil?

It was running fine three weeks ago, then went to start it and found the dead battery now this always something with this project.

jedijeb

No help for an antique

Pelican

You are probably past this for now but my '85 had the same clicking relay when attaching battery. Don't recall what it is for.

AFAIK the ignition boxes rarely if ever fail but I guess it could happen.

jedijeb

First thing I am going to do tomorrow is get the pickup coil for inside the distributor. From what I have read the ignition box is the same as used by Ford around those years and I have replaced one before but it wasn't the problem, always turns out to be the pickup when a Ford stops working it seems.

I noticed on the relay when I was testing the amperage draw, that once you made contact with the probes it would activate and push the amps up close to 1 amp then it would open and the amp draw would fall back down, not instantly but pretty quickly.

jedijeb

Well installed the pickup coil but that didn't fix the no spark problem. But I think I did find what is wrong.


Looks like something might be fried in the ignition module. Dad said to check to see if the back looked melted, and it sure does. Getting a new one tomorrow to see if that fixes it.

Looking at the ignition schematic in the Haynes manual seems there is only this, the pickup module and a Micro Processor Control Unit. It is denoted with a dashed line in the manual which I am not sure what that means, but looking at the wires it doesn't exactly match up with what I see. It shows the orange and violet wire coming from the pickup coil and a dark green and a dark green/black also connecting the MPCU to the Ignition module, but I have a green wire also coming from the pickup coil, so I have three wires coming from there where the schematic shows only two.

Does anyone know where the MPCU would be located? I am thinking inside the cab but not sure where. I hope it is just this module, that is much easier to swap out.

aidman78

Hello,
I know this is an old forum, but i need to comment. i have a 1998 jeep grand cherokee laredo that i bought for my daughter to use. the battery was brand new when i got the jeep, but soon after purchasing it i would find if it sat a few days without driving it the battery would be completely dead. i searched online, asked my mechanic friends and didnt hear of anything that made sense to me. Today i had some time and an empty garage so i again tackled this annoying issue in hopes to get to the bottom of it and finally figured it out:2thumbsup:

I read a lot about the MUX/T TOW fuse that is under the hood as that is where my draw was coming from. about 175ma i read that someone had a bad door switch in the back door (hatch) so i tore in to the door and while having the dc amp meter installed in the 50 amp fuse location started unplugging different connections under the plastic cover of the back hatch and after about minute i noticed the amp draw dropped to 12ma. So I started plugging things back together and found the latch switch for the glass window was the culprit.
so i also left the hatch switch unplugged to avoid that problem later.
I will crack another beer and maybe i will attempt on of my other many tasks.
:cheers2: