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rpmdiag
rpmdiag, Tech and Instructor
Category: Jeep
Satisfied Customers: 7473
Experience:  Since 1975
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2005 jeep grand cherokee laredo 3.7 Last week: Jeep stalled

Customer Question

Hi-
2005 jeep grand cherokee laredo 3.7
Last week:
Jeep stalled after about 5 seconds after cold start
Recranks and stalls within 2 seconds after that
After several recranks, stopped cranking all together. Eventually traced that out to a faulty ground on starter relay circuit.
Towed to home - replaced crank pos senosr, cam pos sensor, and fuel pump.
Eventually replaced PCM this Wednesday and all problems solved.
Car worked fine all day yesterday.
This morning, same exact thing: Stalled, failed recranks, now no crank at all.
Any thoughts?
Submitted: 1 year ago.
Category: Jeep
Expert:  rpmdiag replied 1 year ago.

Hi, I’m Ron and I can help you.
I have been in this business since 1975 and also teach automotive repair. I am confident we can resolve your problem together. Please understand that I don't know your skill level. I can't see, smell, hear, or touch the vehicle either, so it may take a few replies to get to satisfactory results. Please be patient!
I also try to give all of the information you may need, expecting a “positive rating” in return. I will also continue assisting you after you have rated me, if necessary. If there is any reason I cannot get a positive rating, please let me know why “in advance”, so I can go another direction for you. I am sorry you’re having this problem; I’ll help you through it.

Check the ignition switch when this happens for power to the starter solenoid. It's either a bad switch or a security problem.

Thanks, Ron

Customer: replied 1 year ago.
When this happened last week I was able to jump 12 volts to the starter solenoid and get engine crank but still no start. I put in a temporary ground jumper off the starter relay just to have the convenience of key cranking. I was able to run the engine on starting fluid into the throttle body. Troubleshot the injectors. They were getting 12 v on the positive side but not getting the ground to negative from the Pcm. Replaced the Pcm and all was well for two days. The. This morning exact same issue. A stall, several failed recranks and then no crank. Tested 12 v from ignition switch to starter relay. Something else is going on, starter relay is a symptom of this. Not likely to get a new pcm that fails exactly the same as the old one. Thoughts?
Expert:  rpmdiag replied 1 year ago.

Then the security system is causing this. It is NOT grounding the injectors to fire because it's being told the car is being stolen. It looks like only the dealer, a qualified shop or a lock smith is needed to check the computer system and find out where this error is at.

Thanks again and please don't forget to rate me and keep this link in case you need me again later on.

Ron

Customer: replied 1 year ago.
The car did not have an alarm originally, the new pcm is causing the alarm light to flash, however it was working fine. Would the alarm systems I the following: kill power to the fuel pump resulting in s stall after a few seconds, and then kill power to the starter as well as keep the injectors from working? Seems like a lot of layers when any one of them would keep the jeep undriveable. Is this something you have seen?
Expert:  rpmdiag replied 1 year ago.

Yes I have seen this with multiple problems. The procedure I mentioned in the last post is now what needs to be done.

Thanks again, Ron