My 3.9L 1997 dakota has had trouble starting, intermittent stalling. I started throwing parts at it and here is a list of them:

-PCM (ouch in the pocket book, thought it fixed it but was mistaken)
-Ignition Coil ($10 dollar hail mary)
-Cam sensor (needed anyway)
-Crank Sensor ($20 dollar hail mary)
-Cap and rotor (needed anyway)
-Sparkplugs (needed anyway)


After those things I've noted that I'm getting fuel, but at time no spark from the ignition coil (which i've replaced so I know it's good) When I get spark I pop right off.
I thought maybe the wiring from the pcm to ignition coil was bad so i ran a wire directly from pin 6 (black with gray stripe) to the ignition coil. (I got it to run by chance parked it and it won't start again)
So I took an led and wired it up to the negative of the battery and the 12v green with orange stripe and get constant signal (that checks out good).
I took my led and hooked it up to the pin 6 black/gray stripe and the other end of the led to my positive battery terminal. I get a faint light at all time and no pulsing when i manually move the belt so that i can hear my crank sensor click.
From what i was reading it should pulsate when i'm doing this on and off, but it's just a constant faint light.

 

Could be the connector itself is bad, not making good contact, or, another bum PCM......

 

I cut the wire from a few inches off the pcm and ran my own wire because i thought that it might be bad at a splice or something any ideas for wiring on the other side of the pcm?

 

PCM just grounds the circuit, and opens it to fire the coil. That's it. If it isn't doing it, likely the PCM is bad.

 

The PCM likely needs a minimum RPM to trip the ASD relay to provide power to the coil and injectors, and to pulse the cold side of the coil. I don't know that minimum RPM might be off hand if such requirement exists, but that is one of several reasons why these trucks hate low voltage. Spinning over slow combined with insufficient voltage to fire the injectors and coil.

Coil should fire four times per rotation of the crankshaft, so 50 RPM should be 200 sparks per minute, or a little over 3 times a second. You should be able to see that on your LED as you spin the engine around on the starter.

You verified that the 12V side of the coil and fuel injectors has 12V, right? That voltage comes from the ASD relay, which is triggered by the PCM.

 

Yep I'm getting solid 12v from the ASD. I took my led wired it to the negative battery terminal and ignition coil terminal (green/orange) and got solid bright light.
I was moving manually and could hear the click as i moved it around but never saw any change in the led.

 

You shouldn't have ASD voltage with the engine sitting still, except for 3 seconds at key-on. If ASD voltage is always present, that again points to a possible PCM issue.

 

I think we're mis communicating here, Hold on I'll get a video of what I mean.

I get bright light when I crank, so voltage is present when cranking.

 

Ok, that's pretty much the way it is supposed to work. You have bypassed the PCM completely there.

Put your led between the positive terminal on the battery, and the ground circuit of the coil, (wire that goes to the PCM) see if it pulses.

 

That is what my first video is of positive to black/gray ground. I then moved the engine manually and it remains a faint light NOT bright and doesn't pulsate.