# Jeep will not start



## dmallo (Aug 5, 2007)

I have a 2001 Jeep Grand Cherookee and it was working wewll. I stopped at a local store and when I re-insrted the key into the ignition, the car would not start; heard a series of clicking noises throughout the vehicle. Called AAA and had battery jumped; did not fix the problem. Lighst, horn, seats and windows work; Oh yes, don't know if this is relevant, but at the exact instant I inserted the key into the ignition, my passenger pressed the power windows release to close the window. I don't know if this is a coincidence or whether the act of closing the window and starting the key created a short. Appreciate any help.

Thanks,
Don


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## qldit (Mar 26, 2007)

Good Afternoon dmallo, I am not familiar with that vehicle but there does appear to be a rash of similar problems being reported.
Is there any possibility that the vehicle anti-theft system on that vehicle disables both the ignition system and the start system, so as to completely inhibit engine starting?

If this is the case and in view of your report I would suspect that system has adversely been affected by transient generation in the power, probably by that window motor at a critical time and affected the vehicle anti-theft system sensing.

Is the anti-theft system part of the main vehicle computer or separate?

You might get my line of reasoning here and it may give you food for thought or attract further info from someone familiar with that machine.

I have no idea or circuit diagram to advise how to analyse further.

Sorry not much help.

Cheers, qldit.


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## qldit (Mar 26, 2007)

G'day Again dmallo, you might try checking all the door, tailgate and bonnet sensor swithces for operation and condition, it seems that they have involvement and may be causing your problem.
It is a long shot.

Cheers, qldit.


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## dmallo (Aug 5, 2007)

Thanks for the prompt reply. I am having the vehicle looked at today and will psot the finding. I will look into the anti-theft issue.

Regards,
Don


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## qldit (Mar 26, 2007)

Good Afternoon dmallo, from what I can see those Jeep anti-theft systems are designed into many of those vehicles and use logic circuits to disable the run condition, I wasn't able to definitely determine if that disables the crank ability also but it is very likely it does on some vehicles.

It appears that system is very "soft" electronically and prone to malfunction.

I am kind of glad I run a "Nissan Patrol" in it's basic form, but it is very "trucky" to drive.

I am most interested to see what you determine.

Cheers, qldit.


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## dmallo (Aug 5, 2007)

qldit,

Thank you very much for your interest in my problem. The power of the web is amazing where my simple automotive problem can command the attention of someone on the other side of the planet. Well the problem has been resolved and although I would like to say it was an unusual or rare ailment, alas, it was nothing more than a defective battery. It apears that the insertion of the ignition key and the power window activiation was a mere coincidence (although I still beleive that the combination may have weakened the batter).

Thanks for your assistance. I really appreciated your help.

Regards,

Don Mallo,
New York
USA


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## qldit (Mar 26, 2007)

Good Evening dmallo, you are welcome old chap, the interesting thing was that many of the Jeep antitheft systems also monitor battery situation and not only differ in different countries but and can actually record if a "jump start" with leads has been done.
I am amazed at how complex some of those systems actually are.

Yes when a battery becomes old and sulphated, it's internal resistance becomes considerably less, and that could easily explain why other systems could interact with normal operating systems, but yours was probably simply past it's "useby"!

Thanks for the reply, I must remember that one!

Well done with accomplishing a decent fix there.

This site has a tendency to assist both parties when there is a problem, my poor old brain base needs a lot of help here trying to envisage what could possibly be wrong from the information given. It is actually an exercise to try to keep my brain alive!! LOL!

Cheers qldit.


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