Cannot get any spark! So lost on this one.

First and foremost let me apologize for the length of this post, I wanted to fit in as much detail as possible. I do consider myself fairly electro-mechanically inclined and like to fix things without the cost of a mechanic. However I am at a loss.

Let me fill you in on the vehicle at hand. I have a 1998 Jeep Cherokee Sport 4WD with; 6-Cyl. 4.0L, fuel injected, automatic transmission and a command-trac transfer case.

So on with the problem. A few days ago I drove into work with nothing wrong, the Jeep was not acting up in anyway. However when I went to start it up to leave for lunch the engine would not fire. It would turn over with plenty of RPMs. So the first thing I checked was the distributor cap (had been wet and cold for a few days leading to this). I could not find any cracks and or carbon traces on the cap. Next logical thing for me was to check for spark. Took plug wire off cylinder number 2 and held it near a "ground" point (as a friend cranked the engine). No spark was reaching the ground. I then replace that plug wire and pulled off the coil / cap wire off of the cap, and aging held it near a ground. And yet still no spark.

I then picked up a new coil from the local auto parts store (now thinking that this really was not the problem), swapped it out for the old coil and no spark. I hung my hat for the day. Went back the next day prepared for war with my Haynes manual and a bunch of printouts in hand.

First I checked the voltage in the harness connector that plugs onto the primary side of the coil, reading was a constant 4.35 volts (I really cannot see this voltage being correct) with the engine cranking over. Then on a latter try I was only getting 0.4 volts? And with my DMM set to "continuity" the ground side of the plug was opening and closing in time as the engine cranked over.

Then checked the ASD relay, testing the Ohmic value (between terminals 85 and 86 = 73.3 ohms). Next was the continuity between 87A and 30, 87 and 30 with and without 12 volts supplied. Those also tested properly.

Next moved onto the Crankshaft Position Sensor, with my tester across B and C. No resistance (open reading).

Now I am at a loss. Why am I not getting any spark out of my coil? How many volts should I be getting up to the primary side of the coil? What should I check next? I was told to test the Camshaft Position Sensor (would anyone be able to fill me in on how to test the CMP)?

Any help would be greatly appreciated.

I had the same problems on my 99, it sounds exactly like my problem and it was the CPS

first thing is first, check all grounds!!! one from back of the block to the firewall, one from batt to engine behind the dist, one from batt to front x member behind radiator...clean em with wire brush sand paper and throw some dielectric grease on there. check all wires going to anything coil related, and maybe throw some dielectric grease in both sides of the plug wires. check wire from coil to dist cap too.
check for water in teh dist and maybe check timing.

i know when the cps is hot it is suppoed to read between high 100's to 270 ohms. they are only 30$ at rock auto and could be the culprit.
my quick guess is grounds and/or the cps.

Well you answered your own problem, you said the CPS had no resistance. That means it shorted out and is no longer working properly.

I just picked up a '99 2 door, and it was having problems, and wouldn't work. I tested the resistance of the 2 door's CPS vs the resistance of my working '99 4 door, and it read in the vicinity of 200 ohms for the 2 door vs. 650ish ohms for the working 4 door. I replaced the CPS, and I haven't had a problem starting it in 1 1/2 months.

Thank you everyone for your input. After a slight blow to the wallet for the CPS my Jeep is back in action. With most people telling me its the CPS I decided to go back and meter it again with my DMM (the first time I tested it, it was cold and dark out so I may not have made good contact with the pins).

This time in the daylight I found a discrepancy between the CPS readings and what the manual calls for. "If you're working on a 1992 or later model, check the resistance between the B and C terminals (marked on the connector). The meter should indicate no continuity (open)." ~Haynes Repair Manual

The faulty CPS metered 0 Ohms (open) across A and B, and 0.8 Ohms across B and C terminals (this would be the fault). The new CPS reads 0 Ohms across A and B as well as 0 Ohms across B and C.

Thanks again for the help

0 (zero) means no resistance...that is the same as a shorted circuit, or full continuity.

An open circuit, or incomplete circuit would read as infinite resistance, or in effect the same as when your DMM probes are just hanging in mid air, not touching anything.

Either way, good to hear your Jeep is back in action...