Well, the infamous Grand Cherokee stall is back. Problem: engine justs quits periodically, then starts up and runs okay until the next time. I've thoroughly researched this issue and have explored all angles: Replaced the crankshaft position sensor, replaced the distributor along with it's camshaft sensor, replaced the ignition coil. Cleaned all fuses and electrical contact points, including spraying electrical cleaner in ignition switch, swapped out relays, checked electrical grounds to engine, checked for frayed wires, followed every lead I could find... only to have the problem has come back!

Which means it went away for some time. To be more exact, it went away during the cool months of operations. Just about when I was going to pull my hair our after doing all the above, the problem seemed to just go away. The only thing I noticed different in my day to day driving was it was starting to get cooler outside (I live in Tucson, AZ). Afterwhich, I went the whole winter with perhaps a couple "engine stumbles/misfires" letting me know the problem was still there just waiting. Now that it's spring and the temperatures are rising in the 90's again, the exact same problem on a daily/hourly basis has resurfaced :-(

It seems worse and pretty predictable when I let the car sit in the parking lot and I go to start it up at the end of the day to drive home. It'll run a couple seconds, then shut down. Sometimes it doesn't want to restart at all. When this happens, I found out if I disconnect the crankshaft sensor, turn on the power, reconnect the sensor, then crank her, electrical ignition comes back on line and up she starts. It also APPEARS that this method also works with the distributor camshaft sensor. But all of this could just be coincidental, as sometimes it appears if I just turn the ignition on and wait for all the start up indicators to do their thing, then it'll start. I do know for sure that it's an electrical problem as I brought my remote starter (solenoid switch) with me one day and realized I had no spark out of the coil while cranking with the ignition on.

Error codes since I last disconnected the battery are: 12, 43, 37, 17, and 55. I've seen these before and have researched them except for #37 which has to do with the torque convertor solenoid in the transmission. I'm wondering if there's a relationship? Perhaps it's tied into the auto ignition shut-down system?

I beginning to suspect the PCM or one it's internal relays or logic components failing at a certain ambient temperature. Or something else that controls the automatic engine shut down sequence other then the crankshaft and camshaft sensors. Perhaps, as mentioned, the torque convertor relay is involved but I don't know it location or whether it would affect the automatic shut down of the engine. Most Jeep block wiring and computer logic diagrams are worthless for detailed troubleshotting and location.

Any help in this matter would be greatly appreciated. I'm at my wits end and replacing the PCM at $700 just to see IF it fixes it doesn't appeal to me after all I've been through. A $10-30 part is one thing, an $800 "maybe" is something else.

My only lead is the temperature differential.

Please help if you have any ideas.

Thanks,

Marshall

what year and engine? it could be a bad intake temp sensor. and if you want to swap out your PCM, I can get them from the salvage yard for $50. they seldom go bad, but is possible yours is.

#17= Engine is cold to long not going in to closed loop.
#37 trans Temp sensor
# 43 Multiple Cylinder Missfire
#12 Battery disconnect
#55 End of Codes
Your Jeep isnt going into closed loop. Check coolant temp sensor- 02 Sensor- Fuel injectors. You need to get it scanned to see what is really going on.Ive had problems with both 02 and coolant sensors when the engine wont go into closed loop . Hard to tell with out a Scan Tool. Could be PCM check everything else first and you can find one a lot cheaper than 800.

I had a similar problen, changed the TPS and it went away, for the time being anyway. Taking a long drive this weekend. According to the expert at Napa auto parts it was internally shorting out thinking the throttle was someplace other then where it was and shutting the engine off. It you disconnect it the motor will not run. cheap fix
my two cents

what year and engine? it could be a bad intake temp sensor. and if you want to swap out your PCM, I can get them from the salvage yard for $50. they seldom go bad, but is possible yours is.


It's a 1997 2 wheel drive Grand Cherokee with the 4.0 inline six. Automatic transmission. Last night it failed to start after trying all my usual fixes, so now it's sitting dead at my friends house and I'm at a loss at what to do since I've replaced most of the sensors. I do have a big truck and car hauling trailer so I can get it over to a place where they can scan the system. I suppose I could bring it to the dealership and have it hooked to their computer. I avoided this in the past because of the intermittent nature of the problem. But, now she not rolling anywhere.

#17 warning came from the fact that I need to put a new thermostat in her as she was running cold this last winter. I rtemember when the engine light came on. It took a while to warm up and then it went off. So, I don't think it's a problem with the temperature sensor or a "closed loop" situation, whatever that it? The #43 misfire came from a couple nights ago when she was cutting out real bad driving her home. #12 was when I cleaned the terminals on the battery but may also be the casue of the problem as to power getting to the PCM, but last night she gave her last breath and refues to fire at all. When I connect disconnmect the crankshaft positioning sensor I can her relays and some other device on the drivers side clicking on and off so there appears power to the PCM even when she's in her "won't run state". I'm going to go over to my friends this morning with a meter and do some more troubleshooting now that she doesn't run at all.

I know the engine has an auto shut down relay system to protect her from serious damage. From what I've read it's tied into the two main sensors: the crankshaft and distributor ones that have been replaced. Is there any other sensors that are tied into this system that I can check and or replace?

Thanks for you help.







#17= Engine is cold to long not going in to closed loop.
#37 trans Temp sensor
# 43 Multiple Cylinder Missfire
#12 Battery disconnect
#55 End of Codes
Your Jeep isnt going into closed loop. Check coolant temp sensor- 02 Sensor- Fuel injectors. You need to get it scanned to see what is really going on.Ive had problems with both 02 and coolant sensors when the engine wont go into closed loop . Hard to tell with out a Scan Tool. Could be PCM check everything else first and you can find one a lot cheaper than 800.

I had a similar problen, changed the TPS and it went away, for the time being anyway. Taking a long drive this weekend. According to the expert at Napa auto parts it was internally shorting out thinking the throttle was someplace other then where it was and shutting the engine off. It you disconnect it the motor will not run. cheap fix
my two cents

Well, I'll look into that. At this point the jeep died last night and I', unable to get her running. I may have to haul her over to the dealership where they can put their computer on her, but they can ring up a big bill. What made you suspect the TPS? Did you get a TPS error warning at the NAPA dealership?

Thanks for your help. Let me know how things turn out with your repair.

It's a 1997 2 wheel drive Grand Cherokee with the 4.0 inline six. Automatic transmission. Last night it failed to start after trying all my usual fixes, so now it's sitting dead at my friends house and I'm at a loss at what to do since I've replaced most of the sensors. I do have a big truck and car hauling trailer so I can get it over to a place where they can scan the system. I suppose I could bring it to the dealership and have it hooked to their computer. I avoided this in the past because of the intermittent nature of the problem. But, now she not rolling anywhere.

PS. How does the incoming air temperature sensor tie into the equation? Will it actually shut down the engine through the PCM and auto shutdown system? I assume it's located somewhere in the air intake system? I'm going over to my friends house this morning to see if I can't get her running. Any meter test I can perform on the sensor?

[QUOTE=Marsman]#17 warning came from the fact that I need to put a new thermostat in her as she was running cold this last winter. I rtemember when the engine light came on. It took a while to warm up and then it went off. So, I don't think it's a problem with the temperature sensor or a "closed loop" situation, whatever that it? The #43 misfire came from a couple nights ago when she was cutting out real bad driving her home. #12 was when I cleaned the terminals on the battery but may also be the casue of the problem as to power getting to the PCM, but last night she gave her last breath and refues to fire at all. When I connect disconnmect the crankshaft positioning sensor I can her relays and some other device on the drivers side clicking on and off so there appears power to the PCM even when she's in her "won't run state". I'm going to go over to my friends this morning with a meter and do some more troubleshooting now that she doesn't run at all.

I know the engine has an auto shut down relay system to protect her from serious damage. From what I've read it's tied into the two main sensors: the crankshaft and distributor ones that have been replaced. Is there any other sensors that are tied into this system that I can check and or replace?


THE ASD RELAY CONTROLS THE SPARK AND THE FUEL, RIGHT NOW DO YOU HAVE SPARK AT THE COIL WIRE AND FUEL PRESSURE AT THE FUEL RAIL. DALE
jeepman600@sbcglobal.net :grinno:

what year and engine? it could be a bad intake temp sensor. and if you want to swap out your PCM, I can get them from the salvage yard for $50. they seldom go bad, but is possible yours is.

How does the intake temperature sensir tie into the PCM and is it capable of shutting down the ignition through the auto shut down relay system? I can call the salvage yards to se what a used PCM would go for but the yards here are pretty pricy on jeep parts. I don't think any of the normal dealers like autozone, checkers, etc. carry the PCM. I was under the understanding that this is a dealership item only? I just hate to drop the $$ on one at a salvage yard but for $50 I would hesitate to give it a try. Plus it's always nice to carry a back-up unit in case it wasn't the problem.

Thanks

what year and engine? it could be a bad intake temp sensor. and if you want to swap out your PCM, I can get them from the salvage yard for $50. they seldom go bad, but is possible yours is.

How does the intake temperature sensir tie into the PCM and is it capable of shutting down the ignition through the auto shut down relay system? I can call the salvage yards to se what a used PCM would go for but the yards here are pretty pricy on jeep parts. I don't think any of the normal dealers like autozone, checkers, etc. carry the PCM. I was under the understanding that this is a dealership item only? I just hate to drop the $$ on one at a salvage yard but for $50 I wouldn't hesitate to give it a try. Plus it's always nice to carry a back-up unit in case it wasn't the problem.

Thanks

what year and engine? it could be a bad intake temp sensor. and if you want to swap out your PCM, I can get them from the salvage yard for $50. they seldom go bad, but is possible yours is.

How does the intake temperature sensor tie into the PCM and is it capable of shutting down the ignition through the auto shut down relay system? I can call the salvage yards to se what a used PCM would go for but the yards here are pretty pricy on jeep parts. I don't think any of the normal dealers like autozone, checkers, etc. carry the PCM. I was under the understanding that this is a dealership item only? I just hate to drop the $$ on one at a salvage yard but for $50 I wouldn't hesitate to give it a try. Plus it's always nice to carry a back-up unit in case it wasn't the problem.

Thanks

THE ASD RELAY CONTROLS THE SPARK AND THE FUEL, RIGHT NOW DO YOU HAVE SPARK AT THE COIL WIRE AND FUEL PRESSURE AT THE FUEL RAIL. DALE
jeepman600@sbcglobal.net :grinno:[/QUOTE]

I'm going over there this morning to run these checks at your advise is the logical place to start. I can say that I have checked it in the past when she wouldn't run and it was an ignition problem, not fuel. Last time she didn't have voltage at the coil. Last night I could smell the unused fuel when I kept cranking her over, but not the slightest hint of ignition, so I suspect it's an ignition problem, like when I last tested her. I even replaced the coil last time just in case of intermittent internal shorting but the problem seems to be no trigger from the PCM...as to what's causing that, I don't know. I can say that it's not the usual crankcase and distributor sensors. I think either something else is shutting down the ASD relay and cutting off ignition, or the PCM has been going bad and is not supplying the current to the ASD relay. I may be able to check this with a meter this morning as she's finally dead in the sand. But, then she's had a good night's sleep and may just start up when I get there :-) I hate these computer controlled rigs. The old days of stand-a-lone systems were so much simpler when it came to diagnostics.

It's a 1997 2 wheel drive Grand Cherokee with the 4.0 inline six. Automatic transmission. Last night it failed to start after trying all my usual fixes, so now it's sitting dead at my friends house and I'm at a loss at what to do since I've replaced most of the sensors. I do have a big truck and car hauling trailer so I can get it over to a place where they can scan the system. I suppose I could bring it to the dealership and have it hooked to their computer. I avoided this in the past because of the intermittent nature of the problem. But, now she not rolling anywhere.

OKAY, HERE'S THE SCOOP:

I brought it to the dealer for a full computer/sensor diagnostic. The service manager called me up and said “hey fellow you got all kinds of problems”, I said really? He said “yep, you’ve got no MINIMUM AIR FLOW because the little tiny air holes in the throttle body injection system are all plugged up.. they help mix air with the fuel. So, you got lots of unburned gas in the intake manifold” On top of that your injectors are running lean and aren’t spraying the fuel like they should” Oh, I said, first the motor has port fuel injection, not throttle body injection, second how can I have loads of gas with “lean” injectors...that’s an oxymoron. Plus, the thing just passed emissions last week and runs like a top (when it's running). “Well, I’m just the messenger” he said, “we can flush the injectors with cleaner for you, cleaning out all that built up carbon for only $375 and that usually fixes things”. Brother, I thought this is how they take an ordinary guy (usually women) to the cleaners.

I said, but it’s an ELECTRICAL problem that’s shutting the car down, not the fuel...maybe the fuel side could use some maintenance but it’s NOT the main problem. Rather, it has something to do with the PCM and associated circuitry and/or sensors not sending a pulse to the coil..I’ve already verified this with a meter when it wouldn’t start. What was the report on the PCM, I asked? He said, "the mechanic said it checked out okay and that they hardly ever go bad so don't waste your money buying one, plus all the sensors checked out good too. You want me to go ahead with the flush cleaning for only $375"? I said, hell no...that’s just like throwing money down the toilet at this stage, I can get flush at Autozone for less then $10 for the good stuff. Moreover, I'd rather chance it by buying a new PCM because nothing you’ve told me makes much sense as to the problems I’m having and I think I would be better off replacing the PCM. Okay, he said, you make the call...the car will be here waiting for you.

10 minutes later he calls me back and says “you were right, the mechanic ran it for for 30 minutes with no problems, but when he started it up to back it out of the shop it just died on him. He hooked it up to the computer and it said the spark coil “driver” in the PCM failed, which means you need a new computer too” BINGO, I said.....which is what I suspected all along. It appears that an intermittent failing PCM, one that is more prone to fail in warmer temperatures, looks to be the culprit.

Then he says, well Chrysler doesn’t rebuild them so we can get one for you for $700. I said, really, yesterday your parts dept said it would cost me $450 and both Autozone and Checkers sell them for $185. Well, he said, I suppose you can get one of theirs and we’ll marry it (flash it) to your vehicle so it has the proper mileage, VIN# and will run right for only $76.

If I can get this baby running good again for $300 I’ll be a happy camper.

Anyone know if the PCM has to be flashed at the dealer? Will it still woprk without flashing? Is there any other way to enter in the neccessary info without having the dealer do it?

Marshall

the only thing that they would have to program into it would be the vin.the mileage is in the body computer.if you get a used pcm it will have the wrong vin and you cant change it but that wont keep it from running.the only thing to watch out for with a used pcm is if your jeep does not have the factory security system you cant use one from a car that has it.it learns to look for it and if you dont have it you cant disarm it.i dont know what they sell at autozone but it would be worth it to try

I think I saw a 95 4.0 with the PCM still in it at the salvage yard yesterday. Let us know what you decide.

the only thing that they would have to program into it would be the vin.the mileage is in the body computer.if you get a used pcm it will have the wrong vin and you cant change it but that wont keep it from running.the only thing to watch out for with a used pcm is if your jeep does not have the factory security system you cant use one from a car that has it.it learns to look for it and if you dont have it you cant disarm it.i dont know what they sell at autozone but it would be worth it to try

I ordered a rebuilt PCM from Checker-Auto today for $186.99 with a $72 core charge. It's rebuilt by a company named A1 Cardone and has a one year warranty. The salesperson said there was a note in the book that said it has been factory flashed for my year and model, etc and will work upon installed. However, it went on to say that it would need to be flashed in the vehicle to transfer VIN information and to get optimum performance as the vehicle may not run at maximum efficiency or idle at the correct RPM until such operation is performed. How accurate this is and how much is involved is difficult to say. I suppose I will see how she runs after I install the unit and make a decision as to whether it's worth the money to have the VIN flashed. I don't have a burglar alarm system in the Jeep, so maybe that's not going to be an issue, but I wonder about vehicle emission testing when the VIN is no longer in the PCM. There's an ID tag in it's usual place so I don't see that being a problem either. Maybe I'll end up saving myself $76. It'll take a week for the PCM to arrive. One poster said he could get them for $50 at the local salvage yard, but there were none in Tucson and a national search on the hotline only turned up a few and they were all priced from $175 up to 275 used with no warranty, so the Checker route seemed the best way to go.

Thanks

Just cleaning out my mailbox and wanted to let you all know that the Jeep is fixed. I bought a rebuilt PCM ignition computer module from Checkers for $186 and it fixed the problem.

Autozone was a few bucks more but only gave a 90 day warranty as compared to the 12 month from Checkers.

The dealership rang up a total of $3,000 for things they say needed to be fixed, including a $400 fuel system flush that they said was the problem. What a bunch of rip-off artist.

Thanks to all for your help.

Marshall

Screw the stealership. He was so hell bent on selling you a top end clean he didn't even properly diagnose the problem. His dealership is brobably giving bonuses for the advisor who sells the most FI cleanings. I know the Jeep dealership here in Colorado Springs (Lithia Jeep/Chrysler) does give bonuses to their advisors and techs who sell the most of a certain product in a month. Do your homework, find a good used PCM and have it flashed by a different dealership.

Screw the stealership. He was so hell bent on selling you a top end clean he didn't even properly diagnose the problem. His dealership is brobably giving bonuses for the advisor who sells the most FI cleanings. I know the Jeep dealership here in Colorado Springs (Lithia Jeep/Chrysler) does give bonuses to their advisors and techs who sell the most of a certain product in a month. Do your homework, find a good used PCM and have it flashed by a different dealership.

You're right as to bonuses, no doubt in my mind. Due to the intermittent nature of the problem, their diagnostic didn't catch it the first time around. But, after I told him I had personally checked out the system when it was dead and found it to be an electrical problem, he called me back 30 minutes later and said I was right as the engine stalled while the mechanic was backing it up out of the shop. He hooked the diagnostic machine up again and this time verified that the PCM was at fault: the drivers that pulse the coil weren't working. BINGO, which is what all my troubleshooting had led me to believe. The fuel thing and "lack of minimum air flow" is a bunch of BS for the reasons you stated.

As to replacing the PCM, the 12 month warranted unit from Checkers Auto was the best deal I could find even using a salvage dealer's nationwide search. Plus, the rebuilt unit is pre-flashed and checked out at the factory, and therefore, didn't need to be flashed by the dealer...It ran great right out of the box. The dealer wanted $76 to flash the VIN # into the PCM, but the inspection station can earn their money by bending over and get it off the dash as far as I'm concerned.

Thanks

Marshall