95 dodge ram cranks no start

anyone has even seen good injector pulse but no ignition coil control from pcm?
this is old truck with single ignition coil (2 wires, feed and control wire)
cam/crank signals are good ( as expected with injector pulse)
ASD feedback at pcm is battery voltage (loaded test with engine cranking) so good there too

this is full story of the vehicle


vehicle stalled while driving. towed to our shop. NO SPARK.
it has good cam/crank signals. good injector pulse. NO
IGNITION COIL CONTROL. tested at pcm, no control to the
ignition coil all power/grounds to pcm checked out good.
replaced pcm. truck fired up right away and drove fine
during test drive. next day would die after 15 mins of
idle, would restart again but died again. looked like loose
connector to the coil, so replaced it and car would start
again. switched the old pcm back and customer drove truck
home. next day it was no start. we put the new pcm, truck
started right away and drove fine to the shop, only to die
again after 20 mins in idle.

SAME ISSUE, GOOD INJECTOR CONTROL FROM PCM BUT NO IGNITION
COIL CONTROL FROM PCM.

I thought the only 2 inputs to fire both injectors and coil
are cam/crank which are good but looks like something else
internally is telling pcm NOT TO FIRE THE IGNITION COIL.

VERY RARE SITUATION.

first pic is cam/crank signal (ignore the 3rd channel) measured at pcm
second pic is injector pulse/ignition control/asd relay feedback measure at pcm. notice 12V flatline at yellow trace (coil control)

radmilakrejci1 wrote:

looked like loose
connector to the coil, so replaced it

Replaced the coil or the connector?

radmilakrejci1 wrote:

second pic is injector pulse/ignition control/asd relay feedback measure at pcm. noticed no 12-0V waveform at yellow trace (coil control)

Is the trace flatlined at 12V or 0V? I can't view the attachment for some reason??

attachments not viewable.

No parts changed or work prior to this fault appearing ?

ignition coil control wire is 12V flatline
(from Paul and some other tech on IATN I am aware that original coil not replaced for very long time can short out primary and also short PCM driver, but that would flatline 0V)
truck had some work done prior coming to our shop, looks like new tranny was put in, then looks like truck wouldn't start and they were just throwing parts at it, like cap and rotor, new coil wires, new coil and finally new crank sensor.
my customer literally bought the vehicle and it stalled on the drive home, so he towed it to our shop. if it was a crank sensor acting up when truck gets warm, i would have been able to start the truck on cold but it I can't.
checked all grounds/power to pcm with engine cranking no drops out.
this is so rare/unusual and makes no sense, why pcm is not controlling coil driver if it sees good crank signal.

we replaced the coil connector

truck had some work done prior coming to our shop, looks like new tranny was put in, then looks like truck wouldn't start and they were just throwing parts at it, like cap and rotor, new coil wires, new coil and finally new crank sensor.
my customer literally bought the vehicle and it stalled on the drive home, so he towed it to our shop. if it was a crank sensor acting up when truck gets warm, i would have been able to start the truck on cold but it I can't.
checked all grounds/power to pcm with engine cranking no drops out.
this is so rare/unusual and makes no sense, why pcm is not controlling coil driver if it sees good crank signal.