Im sure you have all heard of this problem before. Drove down the street took a left turn and my 96 cherokee stopped running. All electrical still worked and she wants to turn over but just wont run. I have no spark to the distributer or coil. Replaced the coil, 30 amp fuse (tested the rest) and my crankshaft postion sensor. Still wont run. Im out of ideas, any thoughts?

 

Next thing I would try is swapping the ASD relay with another. This relay is located in the power distribution center (black box) under the hood. These relays are all of the same part number, so swapping is not an issue. More on the route of spark for the 4.0 H.O engine below.
If ASD circuit is okay, things still in play include the ignition switch, the computer (rare) and although I've not personally seen it, if the camshaft position sensor fails in a certain way, it could possibly inhibit spark.
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Spark: 12 volts from ignition switch to the ASD relay; when the key is first turned on the PCM provides a ground to the ASD relay to energize it, then the ASD relay passes 12 volts to the coil primary side. If no crank sensor signal is generated after a couple of seconds the PCM cuts the ground to the ASD relay (and fuel pump relay too) and that cuts power to the coil (and fuel pump). Key to START and once again the PCM energizes the ASD relay. Now, a critical element is the crank sensor--no signal from the crank sensor and the PCM won't trigger the coil to provide spark.

 

Also how did u check the cps and what did it read?

 

And what brand cranks sensor did you purchase? No lack of crap aftermarket sensors floating around.....I buy mine only from Jeep.

 

I get mine from oreillys... I always drill mine out though... Never have a problem then... Otherwise they never read right... Biggest issue with the aftermarket ones is they sit to far away from the flywheel...

 

What do you mean by drill them out? Please explain, im a newb to all this. Thanks

 

the mounting holes... take the next size UP drill bit... drill the bolt holes out... then when you install it push it as close to the case as possible and tighten at the same time... this will make it closer to the flywheel and give more juice... the sensor is a magnet and creates its own AC power... closer the magnet is the stronger the current it creates...

 

Thanks ill try that. Gunna be fun getting a drill bit up there...is hard wiring my coil to the battery a bad idea?

 

no dude... take the sensor out... drill the holes ON THE SENSOR... lol

 

u said u tested the CPS though... how did you test it and what was its numbers?

 

I tested the fuses (30a,40a,20a and all the little ones). Tried swapping the ASD and nothibg changed. Just bought a multi meter today. Ill try and do all i can. Thanks for the suggestions.

 

Still dont understand how drillind the mount holes to be bigger makes the crank sensor closer.

 

If you have ever swapped the cps u would see why... Hard to explain... Unplug the cps... Check the ac voltage when u turn the jeep over... Thatll tell u if its bad or not...

 

Ok thanks