2000 Jeep Grand Cherokee 4.7 Engine stalling

Sorry, I forgot to leave out what could be an important fact....

When the shutdown occurred at high speed, and then the engine restarted on its own, a special light came on the dash that I don't recall ever noticing before. I looked it up in my manual, and it was for the keyless sentry system of the Jeep. Hmmmm..... could a malfunction of this key cause a complete electrical and engine shutdown ??

Could I have two very different things going on at the same time ? The high speed shutdown caused by one problem, and the slow idle stall caused by another ??

James

First wiggle the battery terminals to make sure they aren't loose or broken.

High on my list as next culprit is the CPS (Crankshaft Position Sensor) although a failing coil, coil rail, or coil on plug (depends on your system) will also cause these issues without setting codes.

At higher RPM a failed spark will generally not be noticable. I had a run-in with a bad coil in my 93.

Fuel delivery will show up as a power sag or ping at wide open throttle.

Failed SKIM won't shut the engine down once it has started. I think it's a restart gremlin. Starting to point towards a bad connection at the battery or a bad engine ground.

You can. But usually one problem tends to cause others. Oddly though the battery issue usually sets all sorts of codes.

This is starting to sound like a CPS issue.

Doug, you think a bad CPS could cause a total electrical and engine failure at high speed / 70 mph ????

I had thought that the CPS problem only related to starting issues........ but I am not a mechanic.

James

It can. The CPS is used to tell the computer when the engine gets to TDC so it can set timing. Loose that signal and the engine will shut down to prevent misfire.

CPS usually gives grief at low speeds causing a stall as the vehicle comes to a stop. But it's been known to fail at other times.

Check the plug. CPS is on the transmission 11:00 position and usually routs up the passenger side of the engine to the harness.

Thank you so much Doug !!

James

no problem.. hope the info helps.

It's nice to actually see somethign other than the usual noise in this group. :)

Just shoot it, and bury it under your roses. At least your roses will be getting some iron, while you are listening Rush on your AM squawk radio.

Since I first posted this problem, I installed the CPS , about a month ago. So, for a full month, I have had NO problem. But today, at slow speeds of

20-30 mph, the engine shut down completely. Then, the starter would turn over and over, but the engine would not crank. All gauges remained at zero. After some time, and turning the ignition on and off, the gauges went back to normal, and the engine started right up. I am not a mechanic, but it seems to me that this HAS to be an electrical problem.

Yes, I will have a mechanic do the ODC codes asap, but what kind of things are left, that I should be looking for ??

Please read the OP again (below) and give me any hints now, after knowing that I did have the CPS installed.

Thank You.

James

-------------------------------------------

I have a 2000 Jeep Grand Cherokee, 4.7 liter engine. 205,000 miles. Engine has been literally perfect until last six months or so.

In the last week, engine has stalled three times, at very slow idle, or very low speed. I have NO problems starting the engine. Today, while traveling on the interstate at 70 mph, my engine shuts off entirely, and all of my gauges go down to zero. It was as though some one unhooked the battery and the alternator at the same time. I allowed the car to slow down to about 50 mph and all of a sudden, the gauges snap back into "normal" positions, and the engine resumes normal running, and I drive 300 more miles home without mishap, except that it again stalled twice at very low idle speeds (at red lights).

Other than these rather serious quirks, I have good engine performance. No noises, etc. I am not a mechanic, but I would have suspected a fuel delivery problem were it not for the fact that my gauges went dead, which makes me wonder about the computer module or something like that. I have done the ignition switch on and off three times in sequence, but I get no error code. Just reads "done" after the third switch. I hope to get an OBD done asap.

Within past six months I had some slow idle stalling and slow cranking problems. Based on advice here, I had the throttle body cleaned and the iac cleaned out. That took care of those problems at the time. Again, no problems starting now, just slow idle stalling, and the very weird engine and gauge shutdown at 70 mph (occurred once).

Any commnents or advice will be appreciated. What should I be checking ?

James

Sounds like an ignition switch problem...

Probably, given the gauge problems...

Check the connections/plugs to the PCM.

Also check up under the steering shaft where the ignition switch connector plugs into the body connector.

good idea Doug. will pass this along to my mechanic tomorrow.....

James

I wanted to give an update on this ongoing saga. I took the Jeep to a Jeep dealer, and left it there for two days. While at the dealer, it ran fine. They claimed to have driven it some, and they claimed to have let it run at idle for hours at a time, then switch it off and on, etc etc. To make a long story short, they just told me that they could not duplicate the problem, and could not actually diagnose it. They claim to have checked the ignition switch and the pcm plug, but said that was not the problem. They said the problems "could" be the Body Control Module AND the PCM, and quoted me $1,600 for both including labor, but with NO warranty and NO assurance that the car would even run when they got done. I didn't see much future in that, although I would have paid their price if I had some reasonable assurance that would have fixed the problem.

Today, I drove home, a 500 mile trip. The car drove fine for the first

190 miles, and then just shut off, all of a sudden. Same symptoms as shown below. All gauges at zero, but starter would turn the engine over but it would not fire. Very same symptoms as we have had for some time now. We were out of town, and in a precarious spot. We called a wrecker, and waited an hour for them to get there. Once the wrecker arrived and the driver asked me to turn the ignition on and put it in neutral , once I flipped the switch the gauges came on and (as always) the car started fine and ran fine. We drove to a local Jeep dealership, and they said it would be a few days before they could look at it, so we elected to try to drive it home. So, we drove it home for the final 300 miles , without mishap. So, it shut down after 190 miles, then the gauges restored after an hour of shutdown, and them it ran for 300 miles without any problem.

Another thing that concerns and also confuses me..... the Jeep dealer today said that it would be nearly impossible for them to diagnose the problem if it was running fine while it was there. On the other hand, they said that if the gauges were dead when they were working on it..... their computer scanner would probably not get a "read" on the problem, as they suspect there may be a bus communication problem. How on earth would anyone ever diagnose the problem ???

The only pattern that I seem to have noticed, is that the gauges seem to reactivate after about an hour of cool-down. Could this be heat-related ? Is there any type of thermal fuse or in-line link that could cause this problem ??

I will greatly appreciate any further comments or advice on this problem.

James

---------------------------------

Since I first posted this problem, I installed the CPS , about a month ago. So, for a full month, I have had NO problem. But today, at slow speeds of

20-30 mph, the engine shut down completely. Then, the starter would turn over and over, but the engine would not crank. All gauges remained at zero. After some time, and turning the ignition on and off, the gauges went back to normal, and the engine started right up. I am not a mechanic, but it seems to me that this HAS to be an electrical problem.

Yes, I will have a mechanic do the ODC codes asap, but what kind of things are left, that I should be looking for ??

Please read the OP again (below) and give me any hints now, after knowing that I did have the CPS installed.

Thank You.

James

-------------------------------------------

I have a 2000 Jeep Grand Cherokee, 4.7 liter engine. 205,000 miles. Engine has been literally perfect until last six months or so.

In the last week, engine has stalled three times, at very slow idle, or very low speed. I have NO problems starting the engine. Today, while traveling on the interstate at 70 mph, my engine shuts off entirely, and all of my gauges go down to zero. It was as though some one unhooked the battery and the alternator at the same time. I allowed the car to slow down to about 50 mph and all of a sudden, the gauges snap back into "normal" positions, and the engine resumes normal running, and I drive 300 more miles home without mishap, except that it again stalled twice at very low idle speeds (at red lights).

Other than these rather serious quirks, I have good engine performance. No noises, etc. I am not a mechanic, but I would have suspected a fuel delivery problem were it not for the fact that my gauges went dead, which makes me wonder about the computer module or something like that. I have done the ignition switch on and off three times in sequence, but I get no error code. Just reads "done" after the third switch. I hope to get an OBD done asap.

Within past six months I had some slow idle stalling and slow cranking problems. Based on advice here, I had the throttle body cleaned and the iac cleaned out. That took care of those problems at the time. Again, no problems starting now, just slow idle stalling, and the very weird engine and gauge shutdown at 70 mph (occurred once).

Any commnents or advice will be appreciated. What should I be checking ?

James

It would be impossible to give an absolutely positive diagnosis without being able to test it while it was dead. However, neither a bus problem or a BCM would cause the engine to shut down while driving.

The instrument cluster gets it's gauge information from the PCM over the PCI bus. The fact that the gauges fail at the same time the engine quits would have me looking real close at the PCM grounds & power feeds. Maybe even a dying PCM.

That lack of gauges at all (including fuel for example) is a clear indication that the computer is not working or communicating with the outside world or the dash. All the gauges are 'buffered' through the computer, which is why.

The inablity to diagnose is basically because they (the dealer) is unable or unwilling to check hundreds of connectors, wires, and electrical components to find where the problem lies. No surprise, really, as it could take many hours.

Heat related? Probably, but the heat may be very localized--such as a single pin on a connector, or a single wire to a pin, or even a fuse.

Suggestions:

1. Disconnect the battery before doing any of these, and wait ten minutes before doing any of these.

1. Reseat all fuses. All of them!

2. Reseat all relays. Again, all of them, don't try to guess which one might be a problem. Don't say--this is the xyz relay so it can't be guilty: do it anyway.

1. Reseat all connectors, paying particular attention to connectors to the ECM and other computer modules, connectors to fuse panels, connectors to dash, and connectors under the dash. Reseat as many connectors as you can find. When you unplug each connector,

*carefully* inspect the connector for discolored or damaged pins or sockets, discolored wires emerging from the connector, etc.

1. Make sure your ground straps are all good, and tight.

Good map, Peter. Couple of refinements to consider as you do them.

a. look for any sign of corrosion or tarnish on the connectors. I know it smells, but my old MJ gets cranky after trips down to the Texas coast and I finally quit being picky and just pull every fuse, spray the fuse block and fuse pins with WD40 then run them in and out a few times. Blow the WD40 out as a last step or it will collect dirt and crud over time but it's a quick and dirty that works.

b. if you see ANY sign of corrosion (greenish crud on a metal wire or pin) soak the connector with contact cleaner (WD40 works but you have to blow it dry) then try and work the connection to get mechanical cleaning. On older Jeeps the fuse block was located on the firewall (under the dash) where any leak from the brake or clutch cylinders would run down on it. The brake fluid is hygroscopic and essentially pulls moisture inside the crimped connections. I've had apparently solid, clean crimped connections go open from the resulting corrosion inside the insulation and crimp.

The computer signals are low voltage/current so ANY amount of tarnish/corrosion on contacts can result in erratic connections. Your description tells me that you almost certainly have a connector problem. And don't forget those ground points - Jeeps are notorious for losing grounds at those points.

Another update to this continuing saga..... had the Jeep to yet another Jeep dealer in my home town.... Although it was there all day, I have no idea of what all they did to it.... I suspect they just put the OBD scanner on it, and came up with a code. They could have done more, but I have no way of knowing. That is why I prefer a private mechanic, so that I can talk to the human who works on my car. Usually, that is impossible at a dealer.

Findings.... the dealer says is shows an error code of P0725, engine speed sensor function. Based on this, they recommended that I replace the transmission control module, at a cost of $850, with NO warranty , and NO guaranty that is my problem !! Sorry, but I just don't see any future in thowing out that kind of money when even they don't really know what the problem is. I wouldn't hesitate if they would assure me this would fix the problem, and/or at least give me a 90 day warranty. Furthermore, I have had NO problem with the transmission. Remember, this is an engine shutdown problem, with all gauges going to zero. So far, different Jeep dealers have told me that I need a new Body Control Module, New PCM, and new Transmission Control Module. None of them have had enough faith in their diagnosis to guarantee their work.

I then took the Jeep to another private mechanic who has a good reputation, and I reviewed all the the facts with him. He is willing to invest some hours in testing grounds, etc etc, but he recommended one first step before I pay for a full day of diagnostic work. Although I replaced the CPS in April, he indicates that he has installed a number of CPS units that turned out to be defective. He suggests that he first install another new CPS, and also replace the Camshaft Position Sensor as well. Then, we would go from there. This guy is very reputable, and I truly believe he is trying to approach this from the most cost-effective approach.....

Any further comments, based on this new info ?? If I have him replace those sensors, would you also replace the engine speed sensor (code P0725) ??

Thank you very much for your continued input!! This is the most frustrating car problem that I have ever had....

James

------------------------------

I wanted to give an update on this ongoing saga. I took the Jeep to a Jeep dealer, and left it there for two days. While at the dealer, it ran fine. They claimed to have driven it some, and they claimed to have let it run at idle for hours at a time, then switch it off and on, etc etc. To make a long story short, they just told me that they could not duplicate the problem, and could not actually diagnose it. They claim to have checked the ignition switch and the pcm plug, but said that was not the problem. They said the problems "could" be the Body Control Module AND the PCM, and quoted me $1,600 for both including labor, but with NO warranty and NO assurance that the car would even run when they got done. I didn't see much future in that, although I would have paid their price if I had some reasonable assurance that would have fixed the problem.

Today, I drove home, a 500 mile trip. The car drove fine for the first

190 miles, and then just shut off, all of a sudden. Same symptoms as shown below. All gauges at zero, but starter would turn the engine over but it would not fire. Very same symptoms as we have had for some time now. We were out of town, and in a precarious spot. We called a wrecker, and waited an hour for them to get there. Once the wrecker arrived and the driver asked me to turn the ignition on and put it in neutral , once I flipped the switch the gauges came on and (as always) the car started fine and ran fine. We drove to a local Jeep dealership, and they said it would be a few days before they could look at it, so we elected to try to drive it home. So, we drove it home for the final 300 miles , without mishap. So, it shut down after 190 miles, then the gauges restored after an hour of shutdown, and them it ran for 300 miles without any problem.

Another thing that concerns and also confuses me..... the Jeep dealer today said that it would be nearly impossible for them to diagnose the problem if it was running fine while it was there. On the other hand, they said that if the gauges were dead when they were working on it..... their computer scanner would probably not get a "read" on the problem, as they suspect there may be a bus communication problem. How on earth would anyone ever diagnose the problem ???

The only pattern that I seem to have noticed, is that the gauges seem to reactivate after about an hour of cool-down. Could this be heat-related ? Is there any type of thermal fuse or in-line link that could cause this problem ??

I will greatly appreciate any further comments or advice on this problem.

James

---------------------------------

Since I first posted this problem, I installed the CPS , about a month ago. So, for a full month, I have had NO problem. But today, at slow speeds of

20-30 mph, the engine shut down completely. Then, the starter would turn over and over, but the engine would not crank. All gauges remained at zero. After some time, and turning the ignition on and off, the gauges went back to normal, and the engine started right up. I am not a mechanic, but it seems to me that this HAS to be an electrical problem.

Yes, I will have a mechanic do the ODC codes asap, but what kind of things are left, that I should be looking for ??

Please read the OP again (below) and give me any hints now, after knowing that I did have the CPS installed.

Thank You.

James

-------------------------------------------

I have a 2000 Jeep Grand Cherokee, 4.7 liter engine. 205,000 miles. Engine has been literally perfect until last six months or so.

In the last week, engine has stalled three times, at very slow idle, or very low speed. I have NO problems starting the engine. Today, while traveling on the interstate at 70 mph, my engine shuts off entirely, and all of my gauges go down to zero. It was as though some one unhooked the battery and the alternator at the same time. I allowed the car to slow down to about 50 mph and all of a sudden, the gauges snap back into "normal" positions, and the engine resumes normal running, and I drive 300 more miles home without mishap, except that it again stalled twice at very low idle speeds (at red lights).

Other than these rather serious quirks, I have good engine performance. No noises, etc. I am not a mechanic, but I would have suspected a fuel delivery problem were it not for the fact that my gauges went dead, which makes me wonder about the computer module or something like that. I have done the ignition switch on and off three times in sequence, but I get no error code. Just reads "done" after the third switch. I hope to get an OBD done asap.

Within past six months I had some slow idle stalling and slow cranking problems. Based on advice here, I had the throttle body cleaned and the iac cleaned out. That took care of those problems at the time. Again, no problems starting now, just slow idle stalling, and the very weird engine and gauge shutdown at 70 mph (occurred once).

Any commnents or advice will be appreciated. What should I be checking ?

James

Having fought CPS problems with the I6 more than a few times, I can tell you that neither that of those sensors will shut the computer down to the point of killing the gauges. The CPS will cause random shutdowns of the engine and it can be heat sensitive. On GM products, the ECM was the most common culprit - also heat related. I've had the most grief with cheap replacement parts and the best luck using OEM parts for those functions.

First, the crank sensor IS the engine speed sensor to the TCM.

Your "reputable" guy wants to start by throwing parts at it first? Before he checks anything? Before he even tries to duplicate the problem? No guarantee it'll fix your problem either? Just sounds like the cheapest "guess" so far if you ask me. That may translate to reputable to you, but...