# 93 Jeep Grand Cherokee (Electrical Problem)



## shirley morgan (Aug 4, 2007)

When hot the vehicle would not crank.
Replaced crank, cam & temperature sensors, new alternator, new PCM.
I am unable to get fire to my coil which is new also.
Automatic shut down relay is good. 
Have power coming from the PCM to the distributor, but none to coil.
Any suggestions? 
Could the alarm system have anything to do with this problem? If so how do I bypass the alarm system altogether? 
Thank you,
Shirley


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## qldit (Mar 26, 2007)

Good Afternoon Shirley, it is an interesting problem and very likely that you have analysed the problem pretty accurately.

I have no experience with those particular vehicles, but would imagine the system would not be so easy to disable as running or re-routing one wire.

You will notice a similar post as yours also recently, if I can obtain a shematic diagram of that system I will add further info but at a guess can imagine it is quite a complicated fix and may even require another computer.
I expected your post would be answered earlier but it looks like no one has the info you need.

Is that system a "chipped key" or a standard ignition key?

You mention you replaced the alternator, was there any particular reason for this?
Was there any possibility the vehicle may have been started with jumper leads?

I am interested to see how that system actually operates and what components are involved.

Edit. You might try checking all the door, tailgate and bonnet ajar 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.

Sorry no help.

Cheers, qldit.


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## jaggerwild (May 21, 2007)

Hello Shirley Morgan! Again
This is a double post. 
***Mods if you could join the two posts that would be awesome.***
Again Shirley, the factory disarm wire(purple with a white trace) in the driver kick panel. You can't just permanently ground it, use a relay to feed it ground at each start up. Or you'll have problems.
Factory alarms do shut off fuel and spark, but i have a feeling this isn't your problem as I've not seen many witch do this. Not to say that it couldn't happen just that you don't see it that often. So if this be the case(your guess) then your not getting fuel either than right?
When an auto won't start in a "Hot" condition it's more related to the starter then an alarm, if you've replaced it then you might have gotten a bad unit as most after market ones are "rebuilds", meaning they are old starts that the parts company's refurbish after they get them from the customers. 
qldit, could probably tell you more about this as mechanic's see it a lot while working on customers cars and it really doesn't make them look to good when it's been replaced and it's still a bad unit.
OK, so no spark from the coil. you need to check and see if it is getting a signal to the unit from the "PCM'.
If you just have no spark from the plugs then check the coil for spark as well, do this just like you check the plugs for spark. ***NOTE*** HIGH VOLTAGE COMES FROM THE COIL***, use extreme caution when checking this as you can get knocked on your keaster if you make contact with it while sparking.( I should know :4-dontkno)
Hope we helped you, if so let us know.


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## shirley morgan (Aug 4, 2007)

I installed a new pcm and the jeep ran fine for a few hours. I stoped at a store and it would not recrank, although in the start position it will crank and when the switch returns tothe run pisition it dies . So I changed the switch complete. The pcm I had put in was a defect and I am sure this one is not.could the cam sensor or ciol pickup cause this problem. something was said about the starter but Im not quite suer haw it couse this problem because the starter is working fine


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## qldit (Mar 26, 2007)

Good Afternoon shirley morgan, when a computerised system starts but when the switch returns to the run position, it is often due to the air-box connector not being correcly fitted or the engine air intake ducting not being properly fitted.

It sounds like you may have more than one problem and that gets very difficult to guess the cause.

Others will have different ideas.

Cheers, qldit.


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