Oh, for sure, response from the OP is needed about thorough scanning and codes is needed! I would also like the OP to confirm that the "manual" posted by kev2 applies to the trans in question; that it at least looks like what is in the manual. There is a lot of valuable info in that manual, but I hate to wade into it very deep if it doesn't apply.
So to confuse me further, I know for a fact that chrysler/mopar introduced a variable line fluid pressure sensor not so long ago and yes it is PCM controlled (introduce caps here) VIA THE INPUT AND OUTPUT SPEED SENSORS.
End of caps.
So in essence, we are no longer reading actual fluid pressure, but trying to reduce clutch slippage by reading throttle angle and in essence, using a open loop format for the VFS to obtain desired pressure line.
No, I am not joking you. Does anybody object to our having hijacked this thread, should Nickb2 and I take this to PM or the Lounge?
Pressure transducers are usually based on piezo-resistance now. Neither PWM or Hall-effect are involved are involved in reading LP (Hall could be, but I have never heard of a pressure transducer using Hall-effect). Control of pressure, yeah, that is often accomplished by PWM of a valve spool/poppet.
I mis-spoke a bit: without a transducer, control of the LP is "open loop", but control of the trans operation can be (and usually is) "closed loop". "Closed" or "open" depends on how you define the control loop being discussed...