99xj Electrical Issues - Identified, diagnosed, and resolved.

Hi all, My wife called and said the Jeep won't start.
So I figured I would share my story with the crew and place it in a search able area so future electrical sleuths can find it and possibly resolve it faster if they are ever cursed enough to have this problem.

--------- The problem -----------
I went home and found the following.
I was able to get it to start.. but.
It wouldn't run unless the passengers door is open. and if you put your foot on the brake the engine cut off.

The windows won't work unless the passengers door is open, or the drivers door is closed and its not in reverse..

Putting your foot on the brakes kills everything. (engine, lights, .. everything).. Except when the passengers door was open and the drivers door was closed.

but if you can get it to start it runs (until you put the brakes on or put it in reverse or close the pasengers door, or try to put a window down)

Needless to say I was frustrated.

_________________

So I went on a ground search in the engine bay. Refreshed my battery cables, engine ground, chassis ground. and every other ground wire I could think of.

No luck same issues.

------ Resolution (So far it seems anyway; I'll update the thread later if it comes back) -----------

I remember at times before the electric windows were slow, like they were lacking sufficient power. So I started to wonder if they had a bad power connection, and possibly shorting the system and draining the power. I went in search of the power feed and the ground wires, for the electric windows. I was hoping that I could find a common ground post where the lights, and systems were all grounded in the same place. during this search I found that the wires from the windows combine with the wires from the fuel pump in the same loom of wires along the drivers side floor.
so I stepped back and realized that the reason the engine was cutting off was the fuel pump was cutting off.


So I opened up the hatch area and followed the fuel pump harness. and I found two bolts in the drivers side rear 1/4 panel. (behind the spare tire location) These two bolts both had two ground wires on them so and they were loose/ painted over.

I took the bolts out, cleaned up the area and tightened them back down tight.

From then on, I was not able to replicate the problem.
the windows go up and down quickly again, the motor runs, and the lights don't dim when you turn the key on anymore.

So I Think I have found the issue, and hopefully if anyone has the same issues they can use this to resolve it.

also If you think I missed anything please let me know. I didn't take pictures because I've been frantically trying to fix it, and its just boring wires anyway.

Thanks for reading.
_M

Thanks for posting!

Thank you!

That's interesting, because I don't recall ever seeing those problems resolved by those grounds, which are well hidden. A good one to keep in mind.

Excellent post to remember. I will check the those grounds on mine now.

Here's the grounds that muduck18 is refering to (pic kind of fuzzy).

I was in that area the other day checking things out so I figured I better mark the ground designators, connectors, and splice location for future reference and took a pic.

G302 is the fuel pump, driver's door switch, left back up and turn signal lamps..

G304 is a ground for lift gate components like lift gate switch, rear wiper motor, high mounted stop lamp, rear defog..



'99 XJ, 4.0L, Gas, LHD

Yep, He nailed it. Thanks sidewinder for the pic!

Update:

I have put a little over 150 miles on it since the ground fix. with several stops and starts and various other activities... and its still working. so I'm almost 100% sure that was the problem!