My '05 F250 5.4, 74k miles, started throwing the P1633,P0446 and blowing the #10 fuse the other day. It appears that this indicates either a bad canister vent solenoid or the wiring to it. Anybody else have any experience with these symptoms? It appears that the solenoid is special order, so want to make sure I'm fixing the correct component. Anybody know where the solenoid is located? Thanks

 

OK, found the solenoid. I disconnected it and I'm still blowing the #10 fuse. The feed appears to be constant power and it doesn't blow immediately so any ideas? PCM? Anything else on that circuit?

 

Got a couple hours to work on it today and I'm struggling to find a fix.

First the valve: I pulled the solenoid valve out. It checks out at 61 ohms, no power supplied you can blow thru it, I hooked it up to 12V and you can't blow thru it. So the valve at least seems to work. The hose from the valve to the small rectangular box is open as I was able to blow air thru it and it came out the outlet on the box. I can't tell for sure if the hose to canister is open. I'll probably have to pull the canister out to test it.

Second the fuse: (#10 under the hood panel) If I put the fuse in and key on I get voltage across the plug. I apparently wasn't getting a good ground back under the truck b/c I couldn't read full voltage to the frame. The wiring to the valve all looks good, nothing obvious to indicate a direct to ground short.

I'm still searching for an accurate wiring diagram to see what can be causing the fuse to blow even when the valve is disconnected.

Help! Anyone have any ideas? Anything else to check?