5R55W Disassembly

[BrooklynBay]

The port near the servos is the EPC test port. The one near the range sensor is the main test port.

 

[akajammer]

port confirm

The port near the servos is the EPC test port. The one near the range sensor is the main test port.

opps, thanks for that, got them reversed.

what is EPC...electronic pressure control?

->the line pressure(behind DTR) = Drive min. 80-110psi / max. 228-263psi Rev min. 90-140psi / max. 282-350psi
->the pressure control(next to the servo caps) = min. 0-15psi / max. 112-134psi

So, all said, the main port behind DTR is the correct placement for a pressure guage inside the cab. It must be, because it will be the most difficult to plumb in the sensor.

Please excuse my ignorance, but what is the difference between the ports.
What components do each of the two supply pressures control?

thank you master brooklyn

 

[BrooklynBay]

The main port is the actual pressure (cooler lines, valve body passages to the clutch packs, servos, etc), and the EPC port is the pressure that is on the EPC solenoid. You will see that the pressure changes on the main port to represent the pressure on each gear setting since the internal parts are hydraulically controlled. The EPC solenoid regulates the pressure with the command of the PCM. The PCM could request higher or lower pressure depending upon the input of various sensors. The pressure could be increased to a higher than normal level when it goes into FMEM or "limp" mode. This is the reason why it's not a good idea to continue driving with a flashing overdrive light. The extra pressure will compensate for hydraulic pressure which is lost in a leaking clutch pack or a gasket.

 

[akajammer]

The EPC solenoid regulates the pressure with the command of the PCM. The PCM could request higher or lower pressure depending upon the input of various sensors.

so is this to say that if the EPC circut failed, that the main circut would fail as well?
is each circut supplied individually by the pump.
I actually think I remember the frankentranny thread to cover this in part - I'll go re-read.

It would be interesting to have a flow chart of the passageways to each shift cycle and function.
I read a thread on syncro vs non-syncro shifts that either you or glacier posted - I never thought about shift cycles until I read that.

anyway - looks like the main port is the best option for the pressure guage.

just because I am curious about temp also(and sensors are only $10) I am going to install sensors at the output & input cooler lines as well as the pan.
I will simply replace the 1/8" plug that was used for checking fluid level in the pan bottom for the third sensor.
curiosity killed the cat, but not the trans.

OK, now onto the speed sensor issue......
My buddy at ford called me this morning and said that the part #'s when ordering are all the same, so the stamped # must be a lot s/n or something.
He also said from his experience that when these sensors fail, they usually go OL(open line).