I have a 2010 F150 with a 5.4L engine and have started getting code P0446. I have checked the Purge valve and it's not leaking and it is turning on when called to. I took the canister solenoid out of the tank and bench tested it. It seems to work fine. I checked the line voltage and have a solid 12 volts in the power line and the pcm line has some minor voltage in it and in a ohms test it goes to ground. I cleaned the fuel fill flap as best as you can anyway. Anyone have any ideas?

 

Do you have a solid 12 v when the solenoid is turned on? Might have a voltage drop.

 

I'll try back probing it and see what that shows. Thanks for a reply.

 

I have a 2010 XLT 4.6L 3V that is giving me the same code. My vent solenoid passes the bench test and reads 46 ohms between the pins. Power lead continuity down to the solenoid checks out and delivers a solid >12V. Signal wire has continuity back to the 1st harness connector in the engine bay, drivers side above the wheel.

I’m now checking between this harness connector back to the PCM and have an open circuit. Based on another post, the PCM signal is on the Middle Connector Pin-20. Wire color at this harness connector is Green/Blue but at the PCM Middle Connector Pin-20 its Yellow/Red.

Can someone confirm that I’m looking at the correct pin for the Vent Solenoid at the PCM?
Thanks in advance.

 

All is well with the voltage. So I'm still working on a solution. I'm thinking about running new wires as I'm still leaning towards a wiring issue.

 

It is GN/BU all the way from the solenoid to C175B-20. It does not change color.

 

Thank you ProjectSHO89!!! Sure helps when you’re looking at the correct PCM connector.

Once I had the same wire on each end, I put the ohmmeter between the PCM and the harness connector and started squeezing the harness bundle along its path across the front of the engine bay. Ohms were reading ~26M so there was some continuity which was lucky. Once I got close to the harness and especially where my pesky wire peeled off from the main bundle toward the harness, the ohms dropped significantly. Below is a pic showing the trouble spot prior to my repair. Under the insulation, where discolored, the wire had corroded and apparently broke apart inside. Makes me wonder how many other wires are getting ready to fail.


Anyway, the engine light is off for the firt time in a couple years so thats a good start to the weekend. Thanks again.

 

Good follow-up! Thanks for posting your results.