Position #4 fuse continuously blows taking out the following systems.
ABS, TCS, Reverse Tail Lights, Heated PCV. Before I embark on isolating each of these systems, I'm curious about the heated PCV.....has anyone encountered recent failures with this valve and could it be prone to also tripping the fuse because of a failure?

Thanks!
2007 -F150 -- 5.4L

 

Did you have your recall done for the cruise control???


that ABS sounds like its possibly related to that

 

You don't have a Cruse Control recall on a 2007, don't worry about that.

Do you have something like a Recon line of fire, or other add on lighting on the back, that is hooked into the factory reversing lamps.

How about any other modification ? ( reverse sensors, backup camera, etc )

 

No other lighting accessories added to vehicle. The circuit also handles "trailer back-up lights"....but blows with no trailer installed. The fuse blew without using the backup lights. I noticed a few days ago, during moderate acceleration, the ABS/TSC and Brake warning lights flickered -- but didn't come on. Several hours later, the all came on at once. The reason for the instrument notification is because power as been interrupted to key components of these two devices. If it were an ABS or TSC feature....why would it pop the fuse? Why not just a trouble/error light? This is what leads me to believe -- either a wiring harness fault/short or trouble with the heated PCV.....

PS.. I have the Reverse Park Aid option.....but this is factory installed.....

 

Just went to confirm the reversing lamps activating the trailer tow reverse relay, and found something.

Are you sure it is Fuse #4 or is it Fuse #14 ?

2007 2nd printing of the owners manual, Fuse #4 is the DVD battery power and the power fold mirrors, not the list you have. The list you have is Fuse #14.

 

Scully, you're correct! It's fuse #14 -- 10A, not #4...sorry for the confusion. This may all be moot point since I took my truck to the dealership yesterday. I was greeted with the usual $89.00 "evaluation fee"....go figure! Thank you Ford! It's really the "don't bring it to us for work, then turn around and leave and have someone else do it for cheaper after we diagnose" fee!

However, your insight is still appreciated as it will help me wager what needs to be accomplished when I get the dreaded call from the service advisor.
Thank you!

 

Gentleman,
Problem has been solved...thanks to a dealership mechanic. The harness wire which leads to the A/C pressure switch (on this circuit) was damaged (shorted). The service advisor quoted.... $390.00 (including $89.00 "diagnosis fee") labor/cost to slap some electricians tape and a heat shrink wrap on the damaged wire harness and resecure. After reviving myself with CPR, I asked about the eligibility of my ESP warranty -- which is set to expire in 3K. At first, the dealership said no way, not covered. When I balked and said -- I'd pay my $89.00 and take the vehicle elsewhere for the final repair....I get a call back saying they had punched in the wrong part code and yes it was covered by ESP. Amazing, this dealership isn't as stupid as I thought....nor am as much as a "fool" (as they thought) to actually pay almost $400.00 for such a minor repair. Obviously, the dealership will bill Ford from something they most likely didn't fix -- in other words get the same $$$, but in a different manner. Dang, I'm in the wrong business...... Two final questions...
1. I'd like to double check this mechanic's work -- where may I find this A/C pressure switch which in on circuit #14 under the hood? Give me general landmarks and I'm sure I can locate.
2. How can one order the Powertrain/Electrical Service manual for my make/year?
Years past, Ford would supply a order form from "HELM" publishing in the owners guide. I guess they got wise to those owners who actually ordered them and were consequently better educated about parts on their vehicles - the order form is no longer printed in the guide. Ha ha! I sound like a hate Ford. Actually, I'm a diehard Ford (product) fan...but it's the dealership I wouldn't trust for as far as I can spit.

Scully, thank you again!

 

Not sure which AC pressure switch they are talking about ( there is a AC high pressure switch & a AC clutch cycling pressure switch ).

The AC high pressure switch is shown on the location grid as next to the windshield washer reservoir ( must be down by the AC compressor )

The AC Clutch cycling pressure switch is next to the battery b the PCM.

The color codes :

PCM to AC clutch cycling pressure switch : Black w/ Yellow stripe wire
AC Clutch Cycling to AC high Pressure switches : Red w/ Yellow stripe wire
AC High Pressure switch to the central junction box ( in the cab ) Light Blue w/ pink stripe wire ( this is the one that leads to the fuse #14 ).

The connector on the AC Clutch Cycling pressure switch is a 4 pin black connector, only 2 pins used
The connector on the AC high pressure switch is also a 4 pin black connector.

If you want the service manuals in paper copy, Helm Inc still sells them, you can order them online at their web site.

If a PC with a DVD drive is handy, you can troll eBay looking for an outdated one that service guys sell. Just need to set your date back on your PC, before starting it. The service manuals on DVD are subscription based, and they get updates every so often.
Also, you can troll eBay for the service manuals in paper format, to save some $$ over buying new.
I got my paper copy of the EVTM from Helm Inc, then found a paper copy of the 2 volume service manual for cheap on eBay. Also have a DVD from a long time ago, paid 35.00 for the 1996 to 2003, and the 2005 to 2010 ones from this year I got for 55 or 65 I think ( forget, it is a JAN-09 copy ).

 

I actually had this same concern on a customers vehicle last week, however it was not a wiring issue but a bad diode for the A/C high pressure switch.

 

Wouldn't that be Fuse #11, not Fuse #14 if it was the diode ?

 

im not sure i see so many of these things in a day they sometimes blur together

 

Scully, found the manual set on Ebay... $30.00...thank you again! Have a great holiday!