SgtP_USMC

Radi-

Thanks for reading/responding. I tested the plug, and if you were to pull the plug out of the coil and then face it towards you like youre going to plug it into your face, the connection on the left (with the clip facing upward) read .86 volts and the connection on the right read 0.00 volts.

SgtP_USMC

Key was ON

xj_maniac_newb

Then thats the difference in your model and mine. Mine was about an inch from the manifold, and the heat was intense enough to strip all the plastic from the wires.

Radi

You might have to check it while cranking the engine, I'm not sure the ASD relay closes unless you are in "start" or it senses the engine running. Sorry I forgot to mention that.
If it's still the same, there's no power getting to your coil. If that's the case then check the socket the ASD relay sits in, you should have 12V at two pins with the key on. One is to power the relay coil, a second that feeds through the relay to power the coil.

You can check the PCM coil driver as follows:
Connect positive DMM test lead to battery +.
Connect negative test lead to the coil connector terminal that goes to the PCM. (- side)
Crank engine.
You should read less than battery voltage while cranking- typically 8-9 volts. That indicates the PCM is rapidly switching the line on and off of ground as it should. If you had an oscilloscope you would see a square wave there.
(It's OK to try both coil connector pins if you can't tell which is which. The + coil supply connector will read zero or nearly zero since your reference is the + battery terminal)

kennzz05

for what its worth my elec fan relay was actually forcing the female spade clips away from it when i reseated it in the underhood fuse box causing intermittant elec fan operation it felt tight as though it was seating in the wire spades but wasnt. I know its a longshot but just thought since you are going to be pulling that relay several times might wanna check it closely i only figured it out by pulling the dist ctr. and flipping it over where i could observe the wiring being loose good luck
thanks for youre service and sacrifice

kennyWA

Damn, bud. I was sure if you threw a new CPS in that thing it would cure it. I'm stumped. Hope you figure it out soon.

SgtP_USMC

Hey guys,

Yeah I was hoping the CPS would be the issue but alas...its alright. At least when you play the part-buying game you have all new stuff once you finally fix the problem.

So I tested the coil connector at the plug. This time I had someone crank the engine over for me. The connection on the left (looking at it as if you were plugging it into your face, clip up) that was reading .9 or so now read 9.5v on average while cranking. The right side connection read about .5v from 0. Negative lead was grounded and positive lead was stuck into plug.

Any translation? I figure whatever the left side is probably the side that's not causing the issue...

kennz05, it was my pleasure. Its an honor to serve.

Radi

So you have 9.5V applied to the coil. What is your battery dropping to while cranking? The same?
The .5-0 reading on the other side doesn't mean anything since you had the other test lead on ground, not on battery +.
Try measuring the connector on the right referenced to +12V instead of ground (while cranking). What I'm interested in finding out is whether the PCM is switching that connector to ground as it should, or if it's holding it open or closed and not switching.

SgtP_USMC

The battery voltage drops to about 9.5v while cranking. Also, I tested the "right side" of the connector with a lead on the (+) battery terminal and the other lead to the connector, the voltage starts at about 11.5v and drops to about 9v while cranking. (I may not be remembering right because it was pretty early this morning.) I might have to do it again tonight to be sure. For that "right side" connector, should I have the + lead from the meter touching the + battery terminal and the (-) lead from the meter touching the plug?

SgtP_USMC

Just tested the ASD plug with the key on, and I got 12v from two terminals. One was one of the two larger vertical slots, furthest from the three smaller horizontal slots. The other was the top horizontal slot...

...(The ignition coil is brand new, it can't be bad! I replaced it because I thought it might be bad)...

So, according to the tests, I'm getting the right voltage from the PCM at the ignition coil (the terminal on the left as the connector faces you - clip up) which means the PCM is no longer a suspect?

I just now tested the ASD relay plug and it tested good. So does that mean the ASD isn't a suspect either? Does this mean the ignition coil IS getting sufficient voltage?

The mystery continues.

JJCIII

I have the same issue. It threw a p0351. While it was running i jiggled the connector to the coil and almost anytime i did it would die. Im goin to test those wire for high resistance. I have a suspicion that the wiring is corroding inside the insulation and or starting to crack. Test results soon to come.

SgtP_USMC

I ran into a diagnostics procedure at http://www.2carpros.com/questions/je...rokee-no-spark and decided to run through it. I got all the way to the last step, according to this it's the PCM.

This is a good website. Save it!

I guess I'm going to order a remanufactured PCM tonight. I will go ballistic if this isn't the problem, I hate chasing these little gnomes around the engine bay.

MtnHermit

I think you're on to something here.

Back in the day, I had a Cherokee Chief? that would randomly die. This was a big old V8 with its only modern feature a pointless distributor. It had some sort of magnetic pickup instead of points. I suspect most here don't even remember points.

Long/short: The fix was to cut the connector out and solder the wires together. Turns out the magnetic pickup ran at too low a voltage to clean the oxide of the tin plated connectors. The computer industry solved this issue by putting a flash of gold on all connectors.

Bottom line, there's a bad connection here, not a bad part.

Radi

Yes, you had the test leads connected correctly and no, that voltage reading is not right.
The reading at that plug is tracking the battery voltage. It should be lower than battery voltage while cranking because the PCM switches that line to ground only part of the time. If it's tracking battery voltage it would appear to be grounded full time. I'd take a good look at the wiring between the PCM and the Coil, perhaps unplug the connectors @ the coil and the PCM and see if a line is shorted with your DVM.
If the wiring is good, either the PCM is shot or a sensor it relies on to time the spark is bad. (generally that's the CPS)

JJCIII

If it were cps wouldnt it be stopping the injectors from opening?