Fuse box wiring 97 ford expedition

OXY SENSOR IS SHORTED(was)AF (named by Lexus oddly)
THE FUSE BLOWS IF SHORTED DID IT? 25amps blew up?
AND WHICH RELAY, EXACTLY.
both p1135/55 means , B1S1 and B2S1 both front sensor heaters are dead but gee wiz with relay pulled sure they are. dead.
AF heater relay runs both those 2 front O2 sensors
and if either of the 2 short. fuse marked AF heater fuse blows 25AMPS
The heaters are spec at 5 ohms so each heater uses 3amps 6 total paired, and 25amp fuse does not blow.
but if the 2 heaters B1S1 and B2S1, short the fuse blows.
so bad 02 front sensor. or wires to them melted or cut in half
wires on O2 , with clamps missing allow wires to touch 2000f header pipes(exhaust ) and melt and burn up, and then short.
or even burn open.

or put in the wrong 2 front 02 sensors or used the cheap ones
$20 that are hand wired, and wired up wrong.. (done lots but not wrong yet, I'm careful) I run BOSCH only, and or OEM fit
and easy to pop in, the Bosch web site has the Ecatalog to get the correct ones. from them.

Impossible to tell without knowing what fuse number is blowing, along with some basic electrical troubleshooting.
Common suspects include:
altered factory stereo
Aftermarket alarm system
chafed wiring
defective instrument lamp
defective instrument panel

Either the control box has an internal short or one of the sensors reporting to the box is shorted. The sensors work by resistance and send a scaled down voltage signal to the control box. If the wiring or sensor is shorted; a higher voltage may reach the control box and break a fuse. You have to identify the overload to determine if the problem is outside or inside of the control box.

The technique to repair this can be time consuming. This is where the High tech equipment the Dealers have can help. To repair this yourself will take either Ohmmeters or Voltmeters and a wiring diagram and values for the current each carries. A Technician can do this, but the better equipped Repair shops will have plug-in equipment to analyze the components in one or two processes.

This will take the guess work out of the repair and prevent you from replacing good parts without fixing the problem.

You can try to disconnect the plug connectors and check for corrosion. Or look at sensor wires running close to exhaust manifolds checking for melted wire insulation.

The problems can sometimes be sorted out by those which show up on the on-board computer and those which do not.

1. put fuse back in (fire hazzard)
2. check to see if got a broke wire at the trailer connector
3. check wiring under truck at connector see if wire is bad (thats why fuse blown short circuit)

red/yellow leads from the 5amp fuse #29 and red/white leads from 5amp fuse #2. Both of these run into the instrument panel. Let me know if you need more info.

ok there should be 2 fuse boxes on this vehicle one under the driverside dash one under hood your horn fuse is under dash replace and replace your horn high resistance will cause the horn fuse to blow

A fuse blown is a short, and a short is a ahort.
The fuse is the ecm so unplug the ecm and see what happens. If the fuse holds with theecm unplugged, then it is your ecm that needs relacement. If it still blows, The short is in the wiring.go to the parts store and pick up and automatic circuit breaker. It plugs in where the bad fuse goes. It will trip and reset itself automaticallly like a flasher until you have located the short. trick, Start with a breaker of amp. examole; if you took out a 20 amp, put in a 10 amp so the breaker trips faster, On and off quicker so you don't have to wait between ressets. If you want to trace the short by the wiring, put a 25 amp or with great caution a 30 amp. That is the limit. The wire will get warm on the 25 and even warmer on the 30. Pay attention that the wire does not get hot. Hopefully yhe 25 will get the wire warm enough for you to follow. Good Luck, Ned. This method is dangerous if you don't pay very close attention using the high amp breaker. There is a risk of fire if the circuit cannot handle 30 amps. In fact, only yuse the 30 amp breaker if the 25 breaks and resets too fast. Good Luck_Ned_

Since you've ruled out the fuse and the brake sensor switch, based on this diagram from Chilton's: http://www.chiltonlibrary.com/content/images/WD/Ford/167/WD_Ford_167939.pdf
I'm guessing the shift lock actuator itself. I found this is a common Ford problem and found a nice description on how to troubleshoot it. Click below to see Step by step instructions. Hope this helps and best of luck with your problem.

http://autorepair.about.com/library/a/1i/bl660i.htm

found the problem. there are three fuse boxes under the hood. the smallest one on the back corner on the driver side next to the 2nd small fuse box. there are three fuse boxes under the hood and one under the steering wheel. each has fuses for the trailer hitch lights. thanks.

More than likely its being caused by a short-circuit to ground in the wiring in your Cranking Circuit.

If it blows the fuse immediately after installing the fuse, its probably a hot-wire. If it blows it the second you try to crank it over, its probably one of the wires between your ignition and the Starter Relay.

To track down the bad wire you'll need a Wiring Schematic for the vehicle and either a Digital Volt/Ohm-Meter or Test-Light and a basic understanding of wiring which is... honestly a little hard to explain over the internet. However, that is the only course that can be taken without taking the vehicle to a qualified Dealership Technician.