Everything might be a slight exaggeration. But fuse 14 covers Backup lamp and day time running lights relay coil, A/C Pressure Switch, Redundant Speed Control, Heated PCV (5.4L), Trailer Tow back-up lamps, ABS, Reverse park aid, EC Mirror.

This is a 2006. 4.6L V8, SCREW. I don't have reverse park aid. When the fuse blows there is a loud screeching noise from under the hood. Can't identify it because the fuse wont go while I am sitting idling in the driveway. The parking break i9ndicator comes on, the ABS indicator comes on, Cruise control goes away and the A/C quits cooling but still blows. I assume EC Mirror means Electronic Compass Mirror. So I need to figure out where the short is.

I'm looking for loose or broken wires but thinking maybe one of y'all has knowledge of this phenomenon. This really pisses me off because the F-350 is down so I am relegated to driving the emergency back up 1999 F-150.

Thanks,

 

Does the "screeching" occur before or as the fuse blows or after it blows?

I'd unplug the ABS module and see if the intermittent short circuit goes away. Of course, you will not have computer-assisted braking with that disconnected.

"EC" stands for "ElectroChromic" or "ElectoChromatic". Google it, if you're curious.

 

I feel bad for you, been there done that on my 06 Mark Lt. First thing I would check is the wiring at the heated pvc my wiring was melted together, unhooked and fixed the loom side wiring then left the heater unhooked, I thought all was good.....WRONG...lol. Mine would pop fuses clear up to 30a fuse as soon as it touched the fuse prongs. I went as far as removing the engine harness and splitting the loom, then it held a fuse for 15 mins and pop it went. Next removed the ecm and cleaned all mount points and dielectric greased ecm connectors that lasted 1 or 2 days. I bought a short detector still couldnt find it and I was at the point I bought heavy gauge wire and a starter button to let the truck show me the problem..insert wires in fuse holder ...push button and look for smoke....lol. Finally one last thought hit me every time I unhooked ecm it would work for a day, so how I fixed it or got it to stop blowing fuse was unhooking the middle connector and wrapping the loom backwards 1 spin(meaning took the nature wrap out of it) and knock on wood never had a problem since.

I hope this helps, I know I pulled my hair out looking for it. Also how I figured out it was the middle was unhooked the 3 connectors and replaced fuse and plugged them in 1 at a time till the fuse blew. Once again hope this helps.

 

I think it blows AFTER the screech. I'll locate the module and unplug it.

I don't have a heated PCV.

 

Maybe unhook the a/c compressor and see if the screech stops and the fuse stays put

 

The heated PCV is ONLY on the 5.4L, he has a 4.6L.

I considered the AC clutch as source of the noise, but there is no way that a problem with the clutch that would cause it to screech can cause F14 to blow. F14 supplies power to the series circuit of the pressure switches, but that's the limit of the mutual involvement between F14 and the AC system.

 

Yea Op said he didnt have a heated pcv just was sharing my experience, seems how it looks like a/c is out, does it matter if the engine is running or not when the screech happens? How about a video of the noise?

 

If F14 blows, the compressor automatically is disabled.

If it screeches when the engine is NOT running, I'd be looking for an owl or some 80's sit-com character.

 

"I'd unplug the ABS module" Does the engine need to be running for this function? Also I thought asking running or not wasnt a dumb question, also unplugging the compressor is a easy check for the screech and will leave F14 in tack. Maybe the 2 are not related and very possibly is, its going to weird if the screech is gone but the fuse still pops. Also have you spent 3 months finding this problem like I have? Theres so many things on that circuit trying to find the cause makes it difficult.


The more questions and answers about the problem may help narrow it down, also a video may help as well. "I'd be looking for an owl or some 80's sit-com character." And finally being a smart @$$ is that really helping the OP find his problem and make me want to even post to try to help.

 

Alright, here is the situation. Before posting I had disconnected the compass because it was right there and one of the things that are on that circuit. Then I forgot about it. Then I came in the house and posted this thread. After reading the initial responses I unplugged the ABS module. I replaced the fuse and drove around for a while. Nothing happened. Break and ABS lights on. Then I remembered the compass and plugged the ABS back in. I have been driving the truck several miles now. A couple trips to Lowes and everything still works, except the compass. After I get the truck inspected I'll plug the compass in and see if I can blow the fuse. Or maybe the fuse will blow tomorrow. We'll see.

Thanks for the responses. After I finish making the fuse blow, I'll let y'll know what happens.

 

My fingers are crossed for you on a fast fix, if it holds. Some people have all the luck when I unhooked my mirror I broke the windshield when it wouldnt release from the tab, so my frustration level was up there. Keep us posted and good luck.

 

It appears the problem is solved! I was running the truck without the AC connected so I had cruise control, back up lamps, and the other little things. I still had the blower so I could use that on cooler days and I drove the other Ford on hot days. In my truck, one of the problems I had was the AC Blower Motor speed select only had one speed. That is obviously the resistor pack so I ordered one. When I replaced it I decided to reconnect the AC and see what would happen. It has been a couple of months now. Everything works correctly. No more blown fuses and no unexpected starter engagement! Unbelievable. The stealership charged me $90 and told me it was the computer. By the time I got done I had spent over $500 and in the end it was a $25 part.

I hope the next person with the problem sees this post.

 

Thanks for the follow-up. Good man!

 

Yeah, that pretty much is what I think about a blower resistor "curing" what you have now called a random starter engagement (no prior mention).

I'm not much of a believer in coincidences, but I'd put this one into that category unless someone can offer a plausible explication that includes cause and effect.

 

Same (or VERY SIMILAR) problem here. 2008 F150 FX4 after parked in heavy rains, this morning had Brake Warning Light illuminated, ABS Illuminated. Truck drove fine but no A/C or Cruise Control. Guess after reading this thread, I'm going to start pulling fuses, starting with #14.