VetteGuy04

I have a 96 Cherokee 4WD IL-6, was running fine the day before and yesterday got up went out to go to the store and it cranks but will not start. I had bought new plugs, wires, cap & rotar and coil but still nothing, i checked for spark and there is nothing. I'm not electrically inclined can someone help me out?

Forwheeling

I'm having the same issue right now I have a 93. I think it might be the voltage regulator in the alternator but do not know for sure. If you Find the problem please let me know. I will do the same. Thanks

VetteGuy04

no problem

sycoglitch

Possibly the CPS do a search on here for it.
Dukie has a great thread in the stickys section

tjwalker

The #1 cause of no spark on the 4.0 is the crankshaft position sensor. The #2 cause is the ignition coil. Here's more on the route for "spark".

The ignition coil can be tested pretty easily and accurately for primary and secondary resistances with a manual and a meter. The crank sensor can be tested too, but testing is not always conclusive.

If you end up buying a crank sensor, do yourself a favor and buy it directly from Jeep. Aftermarket crank sensors are "hit and miss" with a lot of miss.
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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.

VetteGuy04

I replaced the CPS, had a little trouble getting it out had to put all my extentions together to get a good bite on the bolts but they finally broke loose. Put the new one in and made sure everything was hooked up and she fired up on the first crank. Took it on a little drive and she has more power and runs smooth again.

Thanks for the advice,

tjwalker

Glad we could help. Thanks for updating us; many do not after the problem is resolved.

There are 2 groups of XJ owners.

1. Ones that HAVE replaced their crankshaft position sensor
2. Ones that WILL be replacing their crankshaft position sensor at some time during the life of the vehicle

Roler

True words.

xj guy

So I am working on ruling out my cps in my no start no spark jeep. I have an OHM meter and am trying to check the resistance between the B & C pins on the connector. 4:15 in the video is the connection I have.

Anyways, the Connection I have on my jeep when I place the leads on the CPS in the jeep I am recording about 700 and on the new CPS I bought I am getting about 540 or so. Could this be my problem? In the video he said I should be getting infinite resistance which I am not getting when I do the same test he does.

Will be looking into more options in the mean time.

xj guy

Still not getting anything after I replaced the CPS. I'll have to shoot for the Ignition coil now and see what I get.

survailencewagon

that video was awesome
I like the 30 extension rachet trick

I still hope I don't have to go through all this, but cool video all the same

Wojtas

I had a similar issue a while back on my 01 XJ. It would crank, but wouldn't fire. CPS was replaced, but jeep still wouldn't fire. In my case I needed to get a new ECU (00-01 you need to program the ecu... thanks Chrysler). So yeah, although you might think it's the cps, it might not always be. Glad that it was in your case, cant tell you how much poo I went through to figure out it was a blown ECU.

xj guy

That really is the only way to get to it... unless you cut a hole in the floorboards like some guys do. If you need to get to it I would get a similar set up like he did, but position yourself under the jeep so that your feet are by the passenger door and your head up by the drivers door. With your right arm you can hold the ratchet set up and with your left arm you may or may not be able to wiggle it up in front of the bell housing and reach over and help guide the socket onto a bolt. I would recommend getting the bottom bolt out first as it is less likely to fall into the bell housing, and then instead of trying to pull the top bolt out, Pull the top bolt and the CPS put at the same time. Keeping it together stops the chance of you dropping that bolt into the bel housing.

00_WJ_4.0

Same issue on my 2001 wj. Changed cps...jeep started and i had it running off and on two days. Took battery out again and repaired a few other small issues over two days, replaced the battery again and won't start, cranks but that's it. Nothing from any of the gauges...Tried swapping cps again and nothing at all changed. Temporarily put in pcm, ign, and security module from one of my 2000 4.0 grands and same exact thing happens. At a loss now.

rescue1230

I have the same issue i tried replacing the cps and ecu still no start could someone please help me out