CEL p0453 Failed Emissions -Help! Fuel Cell

I need help, my truck is throwing the CEL. The code is
P0453 Evaporative Emission Control System Pressure Sensor High Input, I have the vent canister hooked up. The stock gas cap, and stock fuel pump o-ring. It is in a fuel cell now. I have a small connector, that comes off the main wire harness on the driver side frame by the rear of the cab. anyone know where this goes? The connector is square and gray. it is a 3-pin. the wire colors are purple?, red, and brown/white? i am thinking this is the problem. i need to know what it hooks up to. i have the connector that hooks up the the canister soleniod. any ideas that could be causing this? i talked to Ford, they wont work on my truck cause the fuel cell. sucks...
they said it could be a connector not plugged, the fuel cell itself, a purge valve, or the fuel canister vapor soleniod.
Please help, emissions due yesterday!
-oh when i moved the fuel canister, i had to cut the wires on the connector, would that make it bad? i figure when the code says "Pressure Sensor High Input" that could mean too much voltage??? i dunno
Thanks
Bryan

duuuuuuuuuude your on here!

its possible that one of the wires is causing to much ohmage. try soldering the connecters and reset the PCM and drive it for a few days.

also check for hi FTP(fuel tank pressure) voltage on the sensor. key on, engine off should be between 2.37 and 2.97 volts. its possilbe its intermintant or the pcm could need a reflash from ford. do you have a chip on there? the fuel tank pressure sensor is supposed to be in top of the tank.

How do i check the FTP? there is no sensor on the stock gas tank...so we didnt put one on the fuel cell. (Is that the gray 90 deg connector on the back of the tank closer to the rear axle?) Where does that connector go to? I thought that went into the filler neck for overflow purposes. I dont have a chip. i have been resetting the PCM by disconnecting the neg batt. for 10 min. Will that work? One the 1st start the CEL is off. But as soon as i start it 2nd time it comes on. I drive the truck 1st time. 2nd start CEL came on.
reset the PCM again started truck for 1 min. started 2nd time CEL on again. I think it doesnt matter if i drive the truck or not, its just the 2nd start that turns it on. Can I dis neg. batt. start truck and drive to emissions. hopefully it would work. obvisiouly i wouldnt have any drive cycles though. so i dont know.
James- since i had to cut the wires and shorten them b/c fuel cell is close to cab, that would cause to much ohmage too huh?
what does a reflash do? thanks guys
Sup baha! yea i know its been a while. been busy working on the truck but this emission thing is killin me...

maybe that 3-pin connector was used to go to the FTP sensor? do you maybe know. if it does i guess i need to talk to Ford and get a new one.

yea its possible that it is, were is hte connector again?

the connector is right off the main wiring harness that runs down the driver side frame. (the wire harness that has the taillights, and ABS sensor) it branches of through the wire loom right under the back side of the cab. it runs right by where i have my rear driverside airbag, and goes back about 1 foot. right where the gas tank would be. i dunno what it goes to, but whatever it goes to i dont have anymore.
thanks for all your guys help.

yea thats prob what it is.

wish me luck, im going to get it tested again. still CEL but only on 2nd start. so im not going to turn it off when u get there .hopefully it will pass then.