Hi guys. I'm trying to diagnose for my uncle who has MS and can't seem to figure out. The truck is too far away to look at but we have checked it out at one time.
Remote start stopped working and throws a p0446 code so canister solenoid and purge valve assembly was replaced along with a smoke test which confirmed no leaks on any of the lines. We tried moving wiring harness around and watched amp meter to see if it would change and nothing was found. Could it be something related to the evap switching valve thats locating on top of the fuel tank? I did take a couple photos of it and connectors looked a little dusty but seemed fine. Any help would be greatly appreciated.

 

Go back and double-check that fault code. P0440 isn't listed as a possible code for the truck you're helping with.

 

My mistake, it was P0446

 

It's not the component on top of the fuel tank.

P0446 indicates an electrical circuit fault in the canister vent circuit

Check the connector at the CV solenoid, make sure it's clean and is properly seated.
Check the coil resistance of the CV solenoid. Should be around 55 +/- 10 ohms.
Verify battery power on the green wire (KOEO) at the CV solenoid.
Check continuity of the green/blue wire from the solenoid connector back to PCM connector C1381B pin 39.

I've seen a number of cases where one of those wires has an open circuit inside the insulation, usually within a foot or so of the CV solenoid connector.

Good luck!