Grrr...I just bought a 2002 F-150 with the 4.6l Triton. I bought it cheap after taking it to an auto part's store to get the Service Engine Soon light on the dash diagnosed. It coded back as a faulty Canister Vent Valve Solenoid. Thought it was going to be an easy fix. After getting under the truck - and discovering a ton of rust - I replaced the valve, canister, and bracket, which I got from the local wrecking yard. Put the new valve on and connected the battery and the light came on after about 15 minutes. I got a meter on the wires and found no power to the solenoid (to either wire) with the key in the "On" position. Now I don't know what the hell to do!!! It appears to be a wiring issue, not a faulty solenoid. Does the power to the solenoid come from the PCM or the purge valve on the engine side of the firewall? I found something about the solenoid should have 1.5 volts going to it, but I'm not sure how to diagnose and find the problem from here. Where would I find a schematic of the EVAP system with the color of the wires notated? (I believe there is a red w/ white stripe, and a green w/ black stripe.) Which wire is the power and which one goes where? Thoroughly confused and need some advice! Thanks in advance!!!

 

What is the actual fault code (Pxxx)?

Most likely, it's a wire broken inside the insulation.

 

I had the same thought/fear as I know little about chasing down a break inside the harness. The fault codes come up p1451, p0453, and p1401, which could all be explained by an unexpected voltage on the vent solenoid circuit. If it was a fault in the PCM I would guess that would be a different error code. Thanks so much for your assessment!