2005 f 450 find fuse for tail/marker lights

no car told
not one clue, year,maker or model
Tail spark, parks go to 4sides 4 corners and lic, lamps. 10 lamps.
even more with parks on mirror L/R

on newer cars there is no fuse,
they use BCM, the body brain.
and it uses smart electronic regulators for lamps
that self correct if the short is cured.
common shorts are, trailer hitch hack jobs.
or collision damage never fully corrected.
MOST BCM slip the park feeds 4 waYS, F/R AND L/R
SO TELL IF ALL 10 LAMPS PARK ARE BAD

THE WORD TAIL WAS FOR TIN LIZZY DAYS, 1 REAR TAIL
AND NOW IS 10 PARKS. OR MORE.
NO CAR TOLD OR I'D OF POSTED THE SCHEMATIC TO IT.

What about them ? What front lights ? Headlamps , park lamps, marker lamps ? They don't work ?

Exterior Lamps
The exterior lighting system consist of the following lamps:
• The Headlamps
• The Daytime Running Lamps (DRL)
• The Clearance Lamps (Y92 roof rack only)
• The Cornering Lamps
• The Front Fog Lamps
• The Rear Fog Lamps (Export)
• The Park, Tail and Marker Lamps
• The Turn Signal Lamps
• The Stop Lamps
• The Backup Lamps

Park, Tail, Marker, License, and Clearance Lamps
The park, tail, marker, license, and clearance (Y92 only) lamps are turned on when the headlamp switch is placed in the PARK or ON position or anytime the headlights are requested. The I/P BATT fuse in the engine wiring harness junction block supplies battery positive voltage to both the park lamp relay switch contacts and the park lamp coil circuit. The body control module (BCM) provides a ground or control circuit to the park lamp relay coil circuit. When the park lamps are turned on, the BCM energizes the park lamp relay. Current flow is from the park lamp relay to the individual park lamp circuit fuses and to their respective park, tail, marker, and license lamps. The front park and marker lamps are grounded at G107 and G103. The tail lamps are grounded at G401 and G402. The license lamps are grounded at G401. When equipped with the Y92 roof rack option, the clearance lamps are grounded at G302. If the driver places the headlight switch in the ON position after the ignition switch has been turned OFF, the park, tail, marker, license, and clearance lamps will remain on until turned off or the battery runs dead.
The T PARK fuse in the rear fuse-relay block supplies battery positive voltage to a separate park lamp circuit connected to the trailer wiring harness.

Your talking about the rear park lamps, but, do the front park lamps work?
Note the picture.
Underhood fuse box, 68 is park lamp relay, 69 is park lamp fuse.

have you checked the tow tail light fuse or the tow tail light relay?

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

they are dual filament bulbs so the tail light filament might have blown and not the stop light , replace the bulb to check

Check the fuse. A bad bulb can cause a fuse to blow.

you have a short somewhere but where ? i would suggest you check the rear lights first including the number plate light ,something is shorting out but its finding it ? best of british with it anyway .

The tail and marker lights and Instrument lights are on the same circuit so both will go out if the fuse for this circuit blows. If fuse continues to fail, check the tail light or marker globes, including the globes for the number plate, for a globe that may have an internal short causing the fault and replace as necessary. As you have already checked the wiring near the light fittings for any chafed wires that could be shorting to the body causing the fault, then a closer inspection of the wires inside all the light assemblies for any shorts may be needed.

It could also be that the instrument dimmer control has failed and is causing the fault. The electronic bits inside the dimmer control for these lights sometimes go faulty. Try disconnecting the connecting plug on the rear of the dimmer control and checking if fuse still blows. If fuse continues to fail, then the fault in the tail and marker lights circuit.

Remove all the tail, number plate and running light globes from the light assemblies and leave the instrument dimmer control disconnected and check if fuse still blows.

Disconnect the plug near each of the light assemblies to see if any of the individual assemblies is causing the fault. With all light assemblies disconnected and fuse continues to fail, then the fault must be in the main wiring loom some where.

If you have a Multimeter, it could be used to determine which light assembly has a fault between the lamp supply and earth connection.

I would start by checking all the fuses, then check the headlight switch,test it for power as you did the tail light, then check the wiring coming out of the cab down the frame to the rear of bed check for a short but if all fuses are good then will not be a short, may be a bad switch and the most important is the bulbs, make sure they are good.

Took it to the shop. The side marker lights were missing on my son's car. The wiring loops from the side marker lights to the tail lights. As the wires were touching in the front, they shorted out the tail lights. Capped the wires, problem solved!
PS: ordered side marker lights, too.