VREF 0.3V 🤕

[JAS1445]

with everything plugged in, the truck is throwing codes for TPS and DPFE. I confirmed ref voltage is nearly 0 with the whole circuit unplugged, including the vref wire from the pigtail at the pcm.

After removing the pin for ftpsREF, the vREF jumped up to a usable voltage and no more codes.

Moving on to the ftps wiring, three wires like you said, ground via pcm, reference voltage ~5.0v, and signal return to the pcm.
Confirmed ~5.0v and the good pcm ground.

Youre saying without internal schematic to stop back probing which makes sense... however, the ftps is separate from the other two sensors. Thats why i wanted someone to back probe that pin at the ftps to get me a voltage at the signal wire to rule out other issues.

Perhaps i could throw a FTPS at it and see what happens, i know for sure it is NOT a pcm, like guided fault finding tells me to replace.

 

[JAS1445]

found 'em

does this match up with your sensor?

no thats fuel rail pressure sensor, im working with fuel tank pressure sensor, mounted in the rear frame rail above the drivers side differential.

i do have access to all of the shop manual for multiple vehicles, im using prodemand

 

[pjtoledo]

I suspect the output is not a stable linear signal, it may be a variable frequency wave form.
can you post a pic of the sensor connector.

 

[pjtoledo]

 

[pjtoledo]

found a source for the confusion.
Ford moved some stuff around.

 

[JAS1445]

Ive ordered a cheap amazon one to throw at it, if it works and nothing else happens, ill end up getting a oe one.

 

[JAS1445]

Update, as of right now no codes and everything is working properly.

I have no understanding of how the FTPS was bringing the VREF down when its a completely different circuit outside of the pcm, but it seamed to be the cause.

Only thing i can come up with, even though the pcm pinout is showing different reference voltages for different things, i think there is 3 on this truck, they must be tied inside of the pcm some how. Ford is too lazy to write that in their diagnostics or i was the first person in the world to deal with this...

Ill update one more time in a bit once its confirmed.