IceFishinFool

I have an 07 screw 5.4. I can not figure out why this fuse keeps blowing and its blowing hard. The inside of the fuse is really wide apart when it blows. Heres what I have done so far and still same result.
Unplugged the followed:
Pcv heater
Back up alarm sensors
Abs module
All abs sensors
Ac pressure switch

After unplugging all that it still blows immediately when I turn the key on. Not sure if there could be a bad relay that is making it blow or if that is even possible. My next option is to start tracking wires but I dont want to start that until I know that I have covered every thing else first. There is an ec mirror on that circuit but I'm not sure what that is and also the relay for trailer back up lights and I dont see where the relay for that is either as it is not listed in my manual. Any help would be great. Thanks fellas!(and ladies)

MGD

Hi.

A long shot, but there are 2 additional items on that fuse:

Trailer tow back-up lamps
relay coil

Back-up lamp and Daytime
Running Lamps (DRL) relay coil

Can't find that relay either ... although the vebiagre fer Fuse #10 says:

Trailer tow back-up lamps relay
(PCB1), Trailer tow parklamp
relay (R201)

... which suggests that relay is non-replaceable and installed on the circuit board of the PJB ( or the fuse/relay box under the hood ).

Does it blow only when you place the truck in reverse?

I do agree with you though - it's likely wire harness tracing is in yer future.

Best of luck!
MGD

IceFishinFool

Thanks MGD. Ill look into those relays. No it blows as soon as I turn the truck on. When I read a post about the pcv heater blowing other members fuse I went and unplugged it and thought that was it as I started the truck and the fuse didnt blow. Then I went out and jumped in and left the house and noticed that the abs/brake light was on again. So I was back as square one again. Now thinking it could have been happening when I go into reverse but now its when the ignition is turned to on so maybe the relay for reverse is just that bad. Ill check and report back. Thanks again.

IceFishinFool

I pulled r201 relay and no change. Looks like I'll be tracing wires. Not fun. Anyways does anyone have wire schematic for fuse 14? Sure would be a ton of help. Thanks in advance.

IceFishinFool

Update.... just unplugged the wire bundle from the driver side door and replaced the fuse and wouldn't ya know the fuse held. So I opened up the bundle and found a broken wire and I'm assuming its for the ec mirror. Fixed up the wire and the fuse is still holding. Crossing my fingers and holding my breath that I have got it fixed as its starting to get humid as hell here and the ac sure would be nice.

zx12-iowa

Nice of you to follow up with results. So many op never complete the circle.

IceFishinFool

Yeah I know. It took me awhile to track it down. I didnt want to start a tread then just let it end with no result as so many do.

IceFishinFool

Can any one help out with a wiring diagram for the circuit as the fuse has started to blow again and i can not figure out why. I want to hook up the ac pressure swtich to a different fuse so at least ill have ac as it is real humid here and would love to have that working. Any schematics of this circuit would be really helpful. Thanks in advance.

Regulator

how many amps is that fuse?

Ford123

The #14 fuse is a 10 amp fuse