You need to make sure the battery is FULLY charged. Also you have to verify fuel pressure with a gauge. And find out whether you have spark. And, I don't see how changing the CPK would fix the communication between the PCM and scanner. Some other issue going on I think.

And btw, any time you unplug or change a sensor,the neg. battery cable should be disconnected.

 

no spark at plugs. tested the middle plug to the distributor with a voltmeter in dc (not sure if thats how i'm supposed to test it?) would start at 10 volts as it started to crank and then drop to 0v within about 2 seconds.
does this sound right for the coil? it doesn't seem like it's right to me...

Battery is fully charged
fuel pressure is good

Not sure why changing the pick-up coil messed with the computer's communication, but that's what happened.

 

"fuel pressure is good" how was it checked? Try holding the gas pedal to the floor while attempting to start the motor for the hell of it.


Unscrew (do not unplug)the precat o2 sensor from the exhaust and see what happens.

 

CPS is camshaft position sensor. CKP is crankshaft position sensor.

CPS controls injector firing and CKP controls the ignition.

 

good fuel pressure meaning i can depress the pin and it sprays up, both after the fuel pump turns on and whenever the engine is cranking. i've tried holding the pedal down.
are you thinking the cat is plugged? doesn't seem to fit my symptoms?
again, no spark at plugs, I tested the middle wire on the distributor, my readings are above. (if i tested it incorrectly please advice)
I will try unscrewing the o2 sensor in the meantime.

 

I don't beleive your statement is entirely correct.

This is directly from the Dodge Manual PDF

ENGINE START-UP MODE
This is an Open Loop mode. The following actions
occur when the starter motor is engaged.
The PCM receives inputs from:
- Battery voltage
- Engine coolant temperature sensor
- Crankshaft position sensor
- Intake manifold air temperature sensor
- Manifold absolute pressure (MAP) sensor
- Throttle position sensor (TPS)
- Starter motor relay
- Camshaft position sensor signal
The PCM monitors the crankshaft position sensor.
If the PCM does not receive a crankshaft position
sensor signal within 3 seconds of cranking the
engine, it will shut down the fuel injection system.
The fuel pump is activated by the PCM through
the fuel pump relay.
Voltage is applied to the fuel injectors with the
ASD relay via the PCM. The PCM will then control
the injection sequence and injector pulse width by
turning the ground circuit to each individual injector
on and off.
The PCM determines the proper ignition timing
according to input received from the crankshaft position
sensor.

 

I read that too and thought that was why I should try replacing the Crankshaft Position Sensor. I am going to write a recap of the situation to make it easier to follow.

Engine died upon filling with tranny fluid
Code reader would not connect to computer (read "error")
No spark condition
Replaced Crankshaft Position Sensor=no change
Replaced ignition pick-up coil=This fixed the computer communication problem. (the code reader will now connect to the computer but there is still no spark)
Cap and Rotor look brand new
Tested coil (not sure if this is correct) with dc volts while cranking.= got 10v immediately and it dropped to 0v within about 2 seconds of cranking
fuel pump/pressure is good, fuses are good, relays are good.

 

You need to check the resistance of the coil.

Remove the coil from the truck. Clean the coil and inspect for cracks. Inspect all terminals and clean if nessesary. Measure the primary resistance between the + and - terminals(they are the terminals the plug goes into). Check the secondary resistance by using one of the primary terminals and the large coil wire terminal. The Haynes Guide lists two coils:

Diamond

Primary resistance 0.97 to 1.18 ohms
Secondary resistance 11,300 to 15,300 ohms

Toyodenso

Primary resistance 0.95 to 1.20 ohms
Secondary resistance 11,300 to 13,300 ohms

If the measured resistances are not as specified the coil needs to be replaced.

 

2 second drop to 0 volts signifies an ASD shutdown of some sort. You should get 12v not 10v. Perhaps this is a simple as a bad battery.

 

will test the coil.

Battery is almost brand new, 4 months old and barely used