Few Issues with 89 XJ

Well after getting this truck this summer and dropping about 600 bucks into it so far (radiator upgrade and removing of ABS system) we are finally putting some miles on the jeep this winter. Having a few issues and looking for some help!

first up is the biggest issue right now and that is that it just randomly started over heating on the way home from work. it was about 10deg outside and the drive was only 15mi but it took 2 hours to get home. The first thing i noticed was that the upper rad hose was not hot, so im thinking air bubble? the heater was also blowing cold.

now after that whole episode, the truck does not want to start. we had killed the batt on the way home (coasting down hill with the motor off an lights on, the batt is pretty old and needs replaced), and now with the new batt it does not want to start. it sat over night in sub 10deg weather. it fired right up but then ran out of gas, put some more in and got it to the driveway and it died and won't restart..

next up is running lights. no tail lights or running lights up front. i pulled all the plugs apart in the rear so nothing was hooked up and it still popped the fuse. ran out of fuses so didnt get much further than that. inspected all the lights up front and the running lights were done, so replacing those. When the truck was overheating we also noticed the headlights flikering a little bit and also got a nice wire burning smell and a little bit of smoke coming from the headlight switch area. there is also another large plug under the dash that is totally burnt up, but we can't find where it would plug into and most everything aside from the dash lights are workign in the car...

any help on any of these would be great, the fuel pump in my GTI crapped out so we started driving the jeep to work and then all this happened so trying to get this stuff sorted and get a reliable vehicle to get to work. thanks!!

First, "burping" the "closed" coolant system XJs is critical.

Park it with a nose-down attitude, remove the temperature gauge/idiot light sender from the driver's side rear of the head--be careful, they break. Now, add coolant to the pressure bottle while observing the port where you removed the sender. When all of the air has come out and you are getting only coolant then replace the sender.

For the future: whenever you replace the thermostat, 195 degree Stant Premium is recommended, drill two small holes in the thermostat flange opposite each other. Drill them far enough in from the outer flange edge so that they won't be covered by the housing or gasket. When installing the thermostat position it so that the holes are at 12 and 6 o'clock. These holes will help with burping. One excellent upgrade is to use the 91+ thermostat housing with the sender port in it. You install a radiator drain petcock in the housing, then all you have to do is park nose-up and open the petcock--instant burping.

Make sure the "NEW" battery has a full charge. Was it brand new or just new to the XJ? Anyway, overnight (Ok) or 24 hour (best) charge. Renew all of your grounds, with particular attention to the dipstick tube--they are for the ICM, ECU, and o2 sensor. The braided ground strap at the rear of the head to the firewall is problematic. The straps degrade, and as it is the ONE AND ONLY ground for the unibody it causes problems. Replace with a cable, and make sure the mounting points are clean and tight.

The coolant system was switched to the post 92 system and 3 core radiator. it was working perfect for probably 600mi or so directly after the swap was done. I am pretty sure that there was not enough anti freeze since i went out today and all the hoses were frozen. I have a theory that something froze and created an air bubble or something and that cause the over heating issue. trying to thaw it out then gonna get back to diagnosing asap

Ralleytuned said:

The coolant system was switched to the post 92 system and 3 core radiator. it was working perfect for probably 600mi or so directly after the swap was done. I am pretty sure that there was not enough anti freeze since i went out today and all the hoses were frozen. I have a theory that something froze and created an air bubble or something and that cause the over heating issue. trying to thaw it out then gonna get back to diagnosing asap

Click to expand...

Note: Things to share with the other children:

Year
Engine
Transmission
Transfer case
Any modifications that may effect or be related to the problem
Any recent changes/repairs

joe_peters said:

Renew all of your grounds, with particular attention to the dipstick tube--they are for the ICM, ECU, and o2 sensor. The braided ground strap at the rear of the head to the firewall is problematic. The straps degrade, and as it is the ONE AND ONLY ground for the unibody it causes problems. Replace with a cable, and make sure the mounting points are clean and tight.

Click to expand...

Not to threadjack, but I just saved an 88 4.0 Cherokee Pioneer for a couple hundred bucks from a friend, and searching leads me here, or to another thread about an ignition swithc..What I'd really like to know, though, if you could help, is WHERE that braided steel cable is supposed to be hooked to!! I found it just hanging from the unibody itself..

History wise, I only know word of mouth on this jeep.. they hit a tree at about 15mph or so, only busted up the front end cosmetically, but they trailered it home and left it to rot (spoiled brats..., anyway). Not sure exactly when it was parked, but someone tried to steal it, and this is when they 'think' all the lights got burnt out in it. When the guy that I bought it off of them got it, they had tried to re-wire all sorts of crazy shit, wires running all over the engine, getting caught in the fan blade when he tried to start it, etc... after he ripped out most of them (the only one he left was the rear running lights, because it actually worked), it started and ran just fine. Now I've got it, and I'm trying to get everything that he didn't fix working. He got the brake lights and the headlights to work. I've gotten all the cosmetic parts, new bulbs, replaced all the fuses I can find... but I still have weird grounding problems when I'm driving down the road, stereo and headlights bounce in and out or dim, shifting from park to drive/reverse/etc causes the same fluctuation in voltage, but my battery is still charging just fine. No blinkers, no front running lights (if I rewire the back ones -proper- they blow the fuse), my heater works but the blower doesn't seem to make more than a draft.. I've been trying to find all the grounds to replace them but I just noticed this grimed up black thing that was literally just hanging there, thought it might be something so I cleaned it up.

WHERE DOES IT GOOOOO?! I've been under here with a space heater for two weeks...:repair:

The one and only OEM unibody ground braided strap goes from the firewall to the rear of the head. Replace it with a good 4 ga cable.

Also good to run a second ground from the negative battery terminal to the passenger's side fenderwell, but not critical.

Ralleytuned said:

The coolant system was switched to the post 92 system and 3 core radiator. it was working perfect for probably 600mi or so directly after the swap was done. I am pretty sure that there was not enough anti freeze since i went out today and all the hoses were frozen. I have a theory that something froze and created an air bubble or something and that cause the over heating issue. trying to thaw it out then gonna get back to diagnosing asap

Click to expand...

when an engine freezes, the water expands and it can easily crack the block and ruin radiators. check for this stuff. it may not of cracked on the outside but may have cracked a cylinder and you may start getting water in the cylinders. hello rebuild and replace

bringing this back up!

most of the issues have been sorted and besides needing to get the brakes bled better it seems to be in decent working order. The one thing we are still working on is the running lights.

Went through and took all the bulbs out, turned the switch on, fuse pops. Then disconnected every single light harness in the whole truck, including the big one in the rear, fuse pops instantly. Figured maybe it was the head light switch so replaced that, and issue is still the same. Right now the dash is all apart and pulling the radio to check to see how that wiring looks (aftermarket cd player). Also pulled the ground cable and cleaned just to be sure that was ok. As far as i can tell when nothing is connected the fuse still pops, so not sure what to look at next haha

Read this site and cherokeeforum.com and i think we have tried just about all that is recommended for this issue, so not sure what else we should try? i found a post about getting wiring diagrams and sent an email but got no reply for the one that i would need. any suggestions much appreciated!

Does the Jeep have a Mickey Mouse trailer wiring pigtail hanging out back? If so, check that out.

cruiser54 said:

Does the Jeep have a Mickey Mouse trailer wiring pigtail hanging out back? If so, check that out.

Click to expand...

Yeah, Cruiser54 is right on checking for funky trailer wiring. You have something connected--shorted--to ground.

one of the first things we looked at. actually disconnected the main rear harness plug in the rear fender. also pulled all the bulbs, and un-plugged every light one by one until they were all un plugged and the fuse still pops instantly.

no bare wire or pinched in the back for the trailer harness, followed all the wires for the front lights back and all the wires looked ok. The one spot i found bunch of messed up wires was at the top of the hatch, the PO had spliced into a few wires (by stripping some of the cover off and wrapping the spliced wire into it and then taping it). Removed all the wires and taped up the bare wires, then taped over the bundle so those should not be grounding out. i plan to go back and repair them correctly in time but i made sure that no bare wire was left so that it cannot ground. Also tested the running lights before taping with every wire pulled apart and not touching metal, problem was still the same.

check the liscense plate light. mine did the same thing (but it was my fault) had the wire swapped when i did a splice

Seems somebody had slightly similar problem, turned out someone had hooked up a power lead as a ground wire in the rear hatch area.

welcome to renix.

Pull the fuse block, you will most likely find that there is a short behind there in the wire that ges from the parking lamp fuse to the dash light fuse.

Both of my 87's had this problem.
While you're there, go ahead and clean the C101 firewall bulkhead connector. I'm saving you headaches later on.

87manche said:

welcome to renix.

Pull the fuse block, you will most likely find that there is a short behind there in the wire that ges from the parking lamp fuse to the dash light fuse.

Both of my 87's had this problem.
While you're there, go ahead and clean the C101 firewall bulkhead connector. I'm saving you headaches later on.

Click to expand...

Thanks for the post, just found it and went out to my garage, sure enough my '88 had the same issue. I can see again!

And the cookie goes to 87manche!

87manche said:

welcome to renix.

Pull the fuse block, you will most likely find that there is a short behind there in the wire that ges from the parking lamp fuse to the dash light fuse.

Both of my 87's had this problem.
While you're there, go ahead and clean the C101 firewall bulkhead connector. I'm saving you headaches later on.

Click to expand...

Gonna go check that right now thanks!

Any ideas or tips on getting the brakes to actually have normal pressure without having to pump them? This is a brand new master cylinder (raybestos iirc) and i have probably bled the entire system 6-7 times. Even tried with the truck running cause nothing else was working...have checked the entire system for leaks, even fixed a bad flare on one of the brake lines.

I have heard that these masters are of pretty poor quality, so we are considering now making the upgrade to the newer setup...

you can bolt on a '96 and up master cyl...its bigger and has a larger vacuum booster...great upgrade!

I dont know why i didn't think of this but i think we may have stumbled on the problem while talking it over with a buddy over some beers this weekend. I have been bleeding from the brake lines since all of the bleeders are corroded and nearly snapped off when i tried to free them...Those being on the TOP of the caliper must be bled to get the air out of the calipers...DUH

gotta figure out how to get those bleeders free.