Of course, we've all read the sticky that tips us to the three red/white stripe wires spliced into one (splice A14) under the PDC. They supply power to the fuel pump relay, ASD relay and pin 3 (BATT) of the PCM.
On my 1993 Dakota (and hopefully on most everybody else s) there is another splice under the PDC involving two blue/yellow stripe wires spliced into one (splice K51) that runs to pin 51 of the 60 pin PCM connector. These wires are the ground return for the coils of the fuel pump and ASD relay. If the ground is open or high resistance, you get no fuel pump and the ASD stops the show. Whether the return from the coil to the PCM signals anything else is another question, but the PCM doesn't seem to throw a code if the coils aren't energized. This leads me to believe the answer is no and what follows should have no negative repercussions.

Pins 11 and 12 are the power grounds for the PCM, they Ohm'ed out good on my ride. The resistance from PCM connector pin 51 back to the blue/yellow splice was less than an Ohm, so the wire and splice are good. The problem appeared to be a high resistance connection at the PCM, it seemed to measure around 75 Ohms from PCM power ground on the passenger side fender liner,through the plugged in connector, to K51.
It may also be that the connection was completely open and what I was measuring was the resistance through the body itself. Rather than fool around at the PCM connection, I just added another blue/yellow wire from the splice under the PDC to the existing, nearby ground on the driver side fender liner. Everything worked. When I turned the key, the fuel pressure went from zero to 40 psi then dropped down to 30 something (vacuum actuated pressure regulator doing its thing).
FWIW, the power out from the fuel pump relay can be detected with a glow type voltage probe at the dark green/black stripe wire (pin 15) on the sky blue connector under the instrument panel (driver side) if the fuel pump relay is doing its thing.
P.S.
OK, I have since learned that the PCM must detect a signal from the distributor during engine start to enable ground at pin 51 and permit continued operation. I have identified the Camshaft Position Sensor at the distributor. Apparently, this is a hall effect device, whose input appears at pin 44 of the PCM. It is beginning to look like the absence of this signal is the probable cause of my starting problem.

Questions to those wiser than myself: Is this the distributor signal that must be seen at the PCM to enable the ASD, fuel pump, etc. for more than the one second engine start window? Next, I suppose I don't see an ASD Circuit code because the ASD relay is disabled by PCM command (no Ground) due to the absence of the distributor signal, which is normal operation of the ASD circuit under the circumstances, does this sound about right? And finally, if any of this hypothesizing is correct, why do I not see a Cam Sync Signal Missing code? I am using an Innova 3140 OBD1/OBD2 scanner with a Chrysler adapter hooked to the grey DTC connector on the Dakota.

 

OK, I have since learned that the PCM must detect a signal from the distributor during engine start to enable ground at pin 51 and permit continued operation. I have identified the Camshaft Position Sensor at the distributor. Apparently, this is a hall effect device, whose input appears at pin 44 of the PCM. It is beginning to look like the absence of this signal is the probable cause of my starting problem.

sounds like you might have it, the hall effect pick up may be the cause?

 

yeah, jump starting isn't like the movies anymore, unless you count gone in 60 seconds. when they jump all those fancy cars with hi tech computerized tools, that looks about right. Make sure you find out the quirks of your dodge before you get too crazy

 

Don't rightly know how anybody gets anything about "jump starting" out of the preceding conversation, but whatever.

Replacing the Hall Effect pick-up partially cleared the fault (see Post Script). It was extremely easy. On the 3.9 liter, you remove the distributor cap and rotor, the pick-up is held by the distributor cap screws. Remove the connector hanging behind the engine, being careful not to damage the connector. Installation is the reverse.
To recap, the signal is needed before the PCM will enable ground to the ASD and Fuel Pump relays for more than a second or two during starting. This fault also kills the injectors and generally does an excellent job of duplicating the symptoms of a bad A14 splice. So if you follow the sticky directions and the fault remains, look here. The definitive diagnostic step was applying a temporary ground at splice K51. If the vehicle runs normally, that about nails it. The part is about thirty dollars, and is known as the ignition pick-up at the auto parts store, its usually a stocked item.
Post Script:
There was more than one problem, after replacing the distributor pick-up, the truck still started hard. I noticed that a ten second wait after turning the key to "on" resulted repeatedly in effortless starting. A fuel pressure gauge showed the pressure was slow to rise and bled down rapidly after the ignition was de-energized. I decided to try the easy fix, replacing the fuel pressure regulator, before bothering with a new fuel pump. That nailed it, the fault is completely cleared. I will install my new Carter P74654M fuel pump at my convenience (since I've already bought one from Amazon) and should be good for another 100k or so of happy motoring.

 

Just a quick chime in here. I have replaced ignition coils and crankshaft position sensors multiple times but not one camshaft sensor yet. Coils will even spark for a test, then spark enough to start but then stall. I've gotten to a point where I keep a spare CKP, CMP and coil in truck everywhere we go. Saves a lot on towing.