Code P1451 - What should voltage to solenoid be?

[Ozz]

Greetings,
I keep getting code P1451 (purge solenoid) and after filling up the other day, I got code P0457 (gas cap loose) too. I checked the solenoid and it does not activate with the key on, engine off. The voltage in the line at the solenoid is 10.6V and the battery voltage is 12.1V. When I took the solenoid off and applied 12.1V, it DID activate.
I also checked the voltage to the tail lamps (since they share a harness with the purge solenoid wire) and they had 10.8 V (KOEO).

A couple questions:
1. Should the solenoid activate (close the air flow through hoses) w/ KOEO?
2. Is 10.6 V normal in that wire?
3. Does the voltage in the solenoid line increase w/ Engine running?

I don't see any chaffing on the harness. It has tape and corrugated tube on it so I don't think it has a problem - at least not back in the trunk area.

Is the solenoid working as it should (not activating w/ 10.6V, does activate w/ 12.1V)?
Should I have more voltage in the wire w/ KOEO?

THANKS!

[RF Overlord]

According to my copy of the Ford OBD-II system operation summary, P1451 is Canister Vent Solenoid Circuit Open/Shorted...nothing to do with the purge solenoid.

Were you under the hood or in the flat black tray mounted under the trunk?

*EDIT* Nevermind...I reread your post and you said you were in the trunk area...anyway, that's the vent solenoid, not the purge solenoid.

*More EDITs* The Canister Vent solenoid is controlled by switching ground, so it is normal for it to have voltage at the connector on Pin 1. When the solenoid is commanded "ON" by the PCM, it grounds pin 2 in connector C450, which is where you were measuring voltage, so if you were using pin 2 as the ground for your meter, you won't get an accurate reading.

[Ozz]

RF Overlord,
Yea, I was measuring across the connector. It dawned on me that I need to see what the voltage was to ground and it was just over 11V.

That said, the solenoid didn't actuate when I plugged it in to the harness but did activate when I jumpered it to the battery (12.1V)... Would this indicate an issue with the solenoid or do I need to keep looking?

Does your OBD II manual say anything about when the solenoid should be activated (to close the air flow)? It doesn't close for me KOEO but maybe it's not supposed to...

Is there anything else in the system that I can test myself at home? I'm wondering if one of the hoses has a leak but finding that will be pretty tough.

THANKS.

[massacre]

To my knowledge, it's not supposed to be powered with KOEO. The PCM commands it to open/close, it's not open all the time.

[RF Overlord]

Unfortunately, what I have is just a summary, not the comprehensive emission repair manual:

"The check is run after a 6 hour cold engine soak (engine-off timer), during steady highway speeds at ambient air temperatures (inferred by IAT) between 40° and 100° F."

I do know the CVS is normally open, and is only closed (turned "on") during the system integrity check that occurs as described above.

Since you say you have VBatt at the connector and the solenoid works when you apply 12V, it sounds like a wiring issue with the ground side that comes from the PCM. My wiring manual is at home so I can't tell you any more until I can get to it, but I do remember there are 2 more connectors involved with this circuit; one is behind the panel in the driver's side footwell, and the other is in the engine compartment. I'll find the pinouts for you as soon as I can...maybe someone else will chime in sooner.

[Ozz]

Thanks for the replies. I have the service CD so I think I can find the pinouts there. I had printed some of it previously and did see the other 2 connections.
Overall, I'm still a little fuzzy as to when the solenoid is activated so that will make it a little harder to figure out what's wrong.
I can do the diagnosis work but I may end up taking it in due to the amount of time it would take and the fact that it's my every day driver. I was hoping it was a straight forward solenoid problem but it doesn't seem so.

Thanks for all the help!

[Ozz]

Well I had the dealership take care of the problem. Turns out it was a wiring issue - not the one just before the solenoid but rather the big one that runs through the left side front wheel well. There were 3 corroded wires.

I had a fender bender 4 years back and mashed up the left front fender pretty good. This is the 2nd time I've had issues related to corroded wires in the left fender. The first time my AC, radio and power steering kept cutting out.

I guess now I know where to look any time I have a possible electrical issue...

Thanks for all the suggestions.