ok let me start off by saying i have owned 11 dodge pickups and durangos. ALL had the 5.2 or 5.9 so i am very farmiluar with this motor. But i did just do a swap on my 97 dakota from a 5.2 to a 5.9 i had laying around. It ran perfect for about two weeks then yesterday it wouldnt start. I thought ok lets check fuel and spark....plenty of fuel no spark. I have replaced the obvious. crank sensor the cam pickup, the coil. checked all grounds and still nothing so i decided i will unplug the battery and see it it helps let it sit for ten minutes with
battery unhooked drank a beer hooked battery back up.
And boom fires up perfectly. I turn off try again boom fires up again. I call it a night go out today an no spark again. Tried doin the battery again and still no fire.
Is this a sign of a bad ecu. I did run into the nobus code on my durango and a new ecu fixed it but i dont want to throw away $200 on one just to try. I have been to local junk yard twice and the pcm is the first thing taken off these trucks they tell me....

ok i have just went and tested the crank sensor i am getting the 5 volt signal at the connector.
So i then moved on to the coil I have 12v on cranking. But i do not have any signal wire voltage when hooked up to a test light

 

On the factory coil, one side is the ASD which will have constant 12 volts, the other side is the coil pulse signal from the PCM. I'm not sure if that signal is +12, ground, -12, or some combination thereof. All I know is that the points connection on my MSD reads directly off of it.

 

As Magnet says, the coil is fed 12 volts. The negative side of the coil is switched, it's the most common way of using a transistor, by the PCM.

Put your meter/light on the negative side and it should pulse.

 

yes i tested the coil the green wire is the constant 12 + side it is getting proper voltage
the black wire 12- side is not gettin a pulse signal.
the crank sensor is testing good at the connector wish i knew witch one it was on the pin on the computer so i could test it there. to test for a break in the wire somewhere in the harness

 

does this look accurate

 

ok so i probed into the connector and yes there is signal coming into the pcm. i tried going from the coil signal on the pcm to the coil. There was still no spark i guess this leads me to assume the computer took a **** is this accurate.

 

PCM completes the ground side of the circuit to fire the coil. If you see 12 volts AT the PCM connector, wiring is good.

If you have a test light, put it across the terminals for the coil connector. Crank the engine, test light should flash. If it doesn't, then, for whatever reason, pcm isn't firing the coil......

Do you have a scanner that can read real time data?? Might want to check and see if the PCM thinks it is getting signal from the crank and cam sensors.

 

thanks heyyou... yeah i am not getting any ground from the pcm. I do not have a good scanner currently. so what next

 

Can you beg/borrow/rent one somewhere? Or borrow a PCM from another truck? Too many other reasons why the PCM may not be firing the coil to just randomly replace it...... although, it IS one of the parts that is suspect....

 

i just moved and dont really know anyone local. I have looked at the junk yard for a PCM. But couldnt find a single one. I know one from a 97-99 dakota durango or ram should run the motor. correct?

List of things i have done so far.
replace and test crank sensor it tested fine. and is sending signal to ecu.
i replaced coil with one i had laying around then tested it it gets the 12v+ side but not the ground from the PCM.
I have checked all grounds they are fine. and i ran three more just to assure myself
i have checked all fuses all good except for one the illum. fuse inside the truck its not getting power? but i dont see how that could affect anything.
i replaced all relays from ones i got from another junk truck.

Last thing i could guess would be a coil pickup but i thought that only controled the fuel witch i have its spark i am lacking.