So I have a 98 cherokee sport with the inline six. The other day started it up to pick up my some from school and as I pulled out of my driveway the engine cut out on me. It will crank over and over but gets no spark. I have replace my cps, cap, rotor, plugs and ignition coil and still nothing. Is there anyone out there that has any ideas whatsoever. Ive been a mechanic for over 15 years and have never had anything like this happen. Any help or advice would be much appreciated. Thank you all

 

ASD relay gone bad? You can swap it with one of the others temporarily.
Is there power to the ignition coil? Negative side pulsed to ground when cranking?

 

Already tried and still got no spark.

 

How do I check the ignition coil?

 

I would check out the new cps. On our 4.0's aftermarket cps's tend not to work and if they do they have a very short life span. The Jeeps 4.0 always seem to be more reliable with only OEM sensors. One other sensor you may want to check out is the cam sensor in the distributor. Hope this helps. Keep us updated on what you find.

 

Other thread about ignition coil testing:

https://www.cherokeeforum.com/f2/ign...esting-148594/

I will also recommend getting a manual - a Haynes, though - which can be found on Amazon for like $3. It is a MANDATORY PIECE OF LITERATURE.

Also, while you're in there, you can do the ignition coil refresh that is one of cruiser's tips - basically bending the prongs back in slightly and cleaning it out with contact cleaner and sanding down the contact if need be. I'd be surprised if the coil itself is bad, but this could be an issue worth trying, since it should be done at least once in the 4.0's lifetime, and takes like 5 minutes to do.

 

Well the ignition coil is brand new. Like two days old new. Was looking through the Haynes and I have gone through everything it points to as well as a few other things my mechanic said.

 

I only go with oem parts. Cps was just installed less than 24 hrs ago as well.

 

Well, if you have no spark, either the coil isn't getting power, or the PCM isn't triggering it to fire. Start by seeing if there is power to the + coil terminal, then check the - side for pulses to ground. One must be missing. Divide and conquer.

 

It might be the ignition module. Take it off and have it checked at Autozone.

 

Every time I look up to figure out where the ignition module is it says I dont have one. It says all I have is the ignition coil

 

You don't have an ignition module.

 

Here's a diagram of the ignition coil circuit.



Note that power from the ASD relay will be available at the coil pin 1 (Dark Green/Orange tracer wire), and that the Gray wire (pin 2) is the ground driver from the PCM.

The power from the ASD relay will only be available when the CPS senses the rotation of the engine and the PCM recognizes the CPS signal.

As the engine rotates there will be a constant 12 volts at pin 1, and a pulse (ground) from the PCM when it sees the CPS signal and the Camshaft Position Sensor signal.

You can back probe the two connector pins using safety pins and hook your voltmeter (+) probe to pin 1 (Dark Green/Orange tracer wire)backprobe and the (-) probe to the engine or battery negative post. While cranking the engine you should see battery voltage (12 Volts).

Once you've established there is 12 volts available, connect the pin 2 (Gray wire) backprobe to the meter (-) probe and the meter (+) probe to pin 1 back probe, then crank the engine. If the PCM is providing a ground pulse the meter should ocillate rapidly.

A test light is not recommended for these tests. Especially the PCM pulse test.

Go here and scroll down to post 53 to see safety pins and pic of back probing with the large #3 safety pin.

https://www.cherokeeforum.com/f2/great-info-threads-here-6558/index4/

Do this and get back

 

In the previous post wiring diagram, did you notice that the coil is engine gounded. That is, the coil itself is grounded to the engine.

When you replaced the coil did you make sure the surfaces of the coil, and the coil mount, are clean and capable of grounding to the engine?

 

Check to see if your jeep has a pick up coil in the distributor. That also controls the spark on the ignition.