CavScout911

Yesterday I was driving (going approx. 50mph) when my Jeep (2000 Cherokee Sport) randomly, and completely, shut off. It started back up and drove for about another 15 seconds than shut off completely again. I had my buddy come out and take a look at it since he's a mechanic, and the only thing he could come up with was the alarm system. The fuel pressure was great, the air intake was great, the spark and fuses were fine. They thought it might be the timing chain, but then came to the conclusion that it wasn't that either. It's not the battery or the starter, because it turns over just fine..it just doesn't kick in.

What my friend thinks is that my alarm system went bad and that it's thinking I'm trying to steal my car, so it won't let it start. I suppose my question is: Is there anything else that could possibly be wrong with it? Also, is there a way to completely disable the alarm system?

Thanks for your time,
Steve

P.S- Someone that I work with suggested that if I just replace the battery entirely, that it might work again. Thoughts on that as well?

VTJeep

More info please. Describe the shutting off part. Just off, or did it sputter, pop at manifold, etc? Just trying to give more accurate answer..

CavScout911

It just shut off, there wasn't a sputter. The only thing really to describe about the shutting off part was that because I was going so fast when it shut off it did a little bit of a jolt.

CavScout911

So I learned that in all likeliness it's not the alarm, could it possibly be the dis module?

THENNING

bad cps can cause those symptoms id look into that

RTorrez1

x2
Sounds like your cps.

OttawaXJ

I had this in my XJ and everyone swore up and down CPS, i replaced it and still did it.

It turned out to be one frigging wire had melted its housing and was shorting with a wire near it causing it to shut down the motor. Why? No idea... However I taped both up and it ran perfect ever since.

I only found this wire after replacing CPS, TPS, MAP, Fuel pump, Fuel filter, the little bumper thingy on your TB that i forget the name of, O2 sensor, ECU, and a few other little things.

CavScout911

Does the check engine light always come on if its the CPS? Because last I checked mine wasn't coming on.

RTorrez1

I know when mine went out Ihad no cel.

Roler

CEL will not always come one with this.PUlling codes ofcourse is a helpfull step in diagnostics.

In any 4.0 ltr engine, the CPS tends to fail at some point eventually.The CPS might be involved in this, however (usually) tends to give you more 'warning' of its malfunction, in the sence of stalling, cutting out etc.
A sudden complete out-of-nowhere shutdown of the engine is not typical for this. Anyway, if CPS is replaced, take a good quality one (from your dealer), since aftermarket ones can still given you trouble, even when you think you replaced them and that "couldnt be it anymore".

Regarding the shutting off, did you have any other symptoms to go with this? did you still have dashlights/other lights? Or was it a complete electric shutdown as well (I know you can crank it now, but not start it): did you check ur ASD relay?

ON the side: when was ur last tune up? Sure about battery/batt connection and grounds? This might be more fore future reference.

CavScout911

My lights, windows, and radio still work. As for the the ADS relay, if I understood what I read than I still have pressure to my gas pump, and the various other things.

As for the side note, my last tune up was about a month ago.

tjwalker

Although there are a number of possibilities, the crankshaft position sensor is absolutely #1 on the suspect list. They often present with "stalling" symptoms before they fail catastrophically.

If you can't find any other root cause, I'd replace it with a Mopar unit purchased directly from Jeep. They are the most reliable and will provide you with the best longevity.

Jaycool25

Is the shutdown very similar to if you were to turn the key back a click while driving? The engine dies but everything else stays on? When it dies, can you simply put it in neutral and start back up again while coasting? If you can does it start easily?

If so this sounds a lot like the problem my GF's 95 had, and the culprit was the ignition switch.
http://www.autozone.com/autozone/par...er=103748_0_0_

Something in hers was failing basically causing it to act like the key was turning it off. I installed a new one in the parking lot of Autozone and its hasn't been an issue since and that was 2-3 years ago now.

What everyone else has said are definitely possibilities too, but I would try the ignition switch, if your symptoms are the same as what I asked above.

Good luck, let us know the fix!

CavScout911

To answer you JayCool, I can't see if it will start again coasting because it won't start at all again. However, when it stalled while I was driving everything did stay on except the engine. Then it just wouldn't start again.

TJwalker, what is a Mopar unit?

tjwalker

Just meant that if you do buy a crank sensor, buy a Mopar crank sensor directly from the dealer. They carry the best crank sensor you can purchase.