Yea they are. The hall device is nothing more than the typical hall device material, it can be a thin sheet of metal or a simiconductive material with three or four wires attached ( depending on application ) to it no resisters, no capacitors nothing. Some hall devices do have there own amplifers, this one does not. The TFI module does that. With out a magnetic field it does nothing. It is no more complicated than a resistor, your would not call a resistor complicated would you?
The TFI is a solid state circuit, but is as dumb as rocks. In it is an amplifier and pass through circuit for PIP ( the signal the hall makes which is very weak ) and a transistor and it's supporting circuits to ground the coil. It has no logic chip, and can not make decisions it is dumb.
The hall effect device does not work by means of positive feed back period.
On a different type of device, lets say a transistor? yea, but not a hall device. It does not work that way.
Read his second post.......again I'll cut and paste it again.
"Thanks Jim, I suspected that was the case since I didn't see a pressure input in the Chilton wiring diagrams and one of the three dealers also said it was a timed even as well. Now to the problem, on ocassion the engine won't start and I've noticed during those times the fuel pump runs continuous in key on position. After cycling the switch several times and I hear the pump stop then I can start the engine. Otherwise I can let the pump run 2-4 minutes and try repeated cranking without the engine starting. It appears the PCM is not completing its start sequence. Is there other test I can perform or should I consider the PCM history. I will add during the on/off switching the voltage is stable to the PCM and other indicator lights on the dash appear normal while in this continuous pump on mode. thanks again"
"Now to the problem, on ocassion the engine won't start and I've noticed during those times the fuel pump runs continuous in key on position."
The mention of running down the battery was as in your case an assumption.
No it does not. The driver may just may have failed or is failing. He may have other problems. You are assuming on false reasoning.
If that's how you check a transistor, so be it.
I didnt say the PCM IS not at fault, I even made several post saying it could be, I just wanted him to know for sure which is it the relay or PCM. I also stated it could be other problems.
I dont work for Ford or at a Ford dealereship.