lurk520

I have this weird problem...sometimes while driving down the road or even just sitting at a light my jeep will die. Sometimes it will start right back up and drive fine...once in a while it doesn't want to start back up, it will crank, barely kick over and die after a second or two. The gauges go wacky when this happens, fuel gauge pings on empty even when its full, I hit the hazard lights and the low fuel light flashes instead, and the volt gauge jumps around. Then after it sits for about 20min. it will start right up and run fine again. When it dies in either fashion, the radio station pre-sets are wiped out, as if it lost its power supply. I plan on replacing my cps but I would also like to check my grounds. So I've researched there is a ground on the firewall and one on the dipstick bracket, but how many more are there? Do I need to follow each one to both ends and check their condition? Any feed back from knowledge or experience would be appreciated. Thanks.

tjwalker

1. Your symptoms sound very much like a crank sensor going south. I would suggest replacing it. I buy mine directly from Jeep for best reliability but I have heard that they currently have a supply issue with a huge backorder, but I would check anyways. Some aftermarket crank sensors are junk and don't hold up.

Here is a thread from another Jeep forum that I frequent. Read the post from Tim very closely. It contains comprehensive information about the crank sensor (including the symptoms of fuel and voltage gauge acting strangely, which is what you indicate).

http://www.jeepforum.com/forum/f11/c...ailing-639123/

2. Refreshing grounds is a GREAT idea. Here is more.
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Grounds can be the root cause of many electrical gremlins. Refreshing grounds is NEVER a bad idea!

You can't just check or look at these grounds. You must remove, scrape, clean until shiny the cable/wire ends and whatever they bolt to. The one on the back corner of the head, and where it attaches to the firewall. Scrape the paint from the firewall. Best to replace that woven cable with a #4 or #2 gauge cable. You can attach the one end to the intake manifold if you would like.

Next go over to the engine dipstick tube stud. Remove the nut and clean the wire ends and scrape the block until shiny at the stud. Reattach tightly.

If you are so inclined, add at least a #6 cable from the negative terminal of your battery to one of the bolts on your radiator support. Scrape the paint off first.


Good luck on this. Your plan is solid. A new crank sensor and fresh grounds will hopefully set you up. Let us know how this turns out.

lurk520

Thank you very much for the info. The problem is so random. The first time it happened it died at idle and started right back up. Then a month later it happened slowing down for a school zone, then didn't want to start back up till it cooled. Then I put it in the shop for a week, they couldn't find anything wrong (a lot of help they were), I got two good ideas reading on this forum in 20 minutes. Now a month later it happens again going through a 4-way stop. I just dread it happening in the middle of a major intersection during rush hour traffic. I will definitely try these solutions.

lurk520

New crank sensor and trans mount installed today. Won a Mopar Crank Sensor on Ebay for 15.50! Had the sensor along with the mount (provided by the shop) installed at a shop for $175. Since they do the sensor by lowering the engine/trans, I decided to have them install a new tranny mount while the cross member is off. I've cycled through my gears a bit and the shift clunk seems to be gone. As for the random stall only time will tell. I tried to clean up the wires that are connected to the dipstick mount, but when I turned the nut, the bolt began to spin with it and it was twisting the wires. So I just wiped it down with out taking it apart, there was quite a bit of oil and grime on that area. I looked for the ground on the fire wall but I didn't see it?

tjwalker

Wow. That shop shouldn't charge you to lower the engine transmission to replace the crank sensor. It absolutely is NOT necessary! You may want to consider a different shop.

But now it's done and you've got a tranny mount replaced.

There should be a ground from the back of the head to the firewall. If there isn't, it has disintegrated and you need to rig one. These are a very fragile grounds, lame from the factory IMHO.

lurk520

Maybe lowering the engine/trans isn't absolutely necessary, but is it possible that it's the safest way not to cross thread a bolt or drop one in the Bell Housing? I wouldn't know since I didn't do it myself. I wanted to do it myself but I got paranoid about dropping a bolt in the Bell Housing. Plus I figured if the shop wants to lower the engine/trans then I might as well have them do the trans mount and kill two birds with one stone. To be honest I haven't found a shop yet that I have full confidence in, some times I'm just willing to pay for convenience. I will have to look a little harder for that ground. Is it possible that different year 4.0's have different ground set-up's?

lurk520

Hey I found my ground strap today, it was hanging down by the crank sensor with the end missing that connects to the firewall, and the bolt on firewall was hand loose, time to make a new ground wire!!