On the 2005 F-550 tow electrical rear plug internal male that hooks op to my truckcamper and a toad... I can only get parking lignts. I can not get brakes light on the camper to light or emergency or turn signals to flash. I replaced blown Fuse #9 (20a) in the Power Distribution Box under the hood (Trailer tow turn signals). I also replaced fuse #38 20a in the passenger compartment Fuse panel called Trailer tow park lights. I need to replace the fuse #107 20a
called trailer tow battery charge but parts store did not have on in stock. but this should not impact turnsignals or will it?

Are there any other fuses that should be checked for blown fuses?

 

Sounds like you have a short in your wiring somewhere. With that many fuses to your trailer and tow lights blown.

 

Are you testing this with or without the trailer actually attached? I had mistaken a problem for no ground. But then again....you are getting tail lights. Are you sure it is the truck wiring though? Have you tried the trailer on another vehicle?

 

similiar thing happened to me when the wifey plugged the 7 pin in upside down. i got lucky and it only fused the trailer running lights relay closed. had to replace both male and female plugs and numerous fuses. the wires at the receptacle got very hot. have the new fusses blown? are you getting power to the appropriate pins? as for troubleshooting, i think all the wiring harness for the trailer starts at the the pwer dis. box under the hood, cant remember exactly but maybe 2-3 connectors before it reaches rear of truck. pita but i agree with previous post you might have a short you need to isolate or just buy new wiring harness from powr distribution box back
btw on my 04 250 i have what the ford techs tell me is an unserviceable relay in the cjb central junction bofuse box drivers side) this info came from their trouble shooting manual.
good luck

 

The trailer and camper connection have been working correctly with the rear connector of the F-550. I had just hauled the boat out of the lake and driven to the city to leave at the boat dealerthe lights were working according to my wife who followed me from the lake to the city. I disconnected the boat trailer and drove 5 miles and wanted to tow the toad truce home but the lights on the camper and toad truck would not function. Had the wife follow me home close so I could check fuses. That is when I found the two fuses blown and replaced them. All the toad truck lights work and all the hauling truck lights (F-550 work) it is just the Tow vehicle plug that does not work because the camper and toad are not getting signal (tested by connecting plug to both camper and toad units ) Have not tested with a multimeter or ground detector.

 

I saw another post a couple days ago about fuses under the hood, near the firewall on the left/drivers side. It these were blown, truck lights work but some of the trailer lights do not.

 

so no voltage to the pin on the connector when you apply the brakes or turn signals. i would imagine you haved checked all fuses? i would r/r any fuse dealing with the trailer tow in the owners manual. next, can you access the wiring connector under your tow vehicle and disconnect the closest plug to the actual 7 pin connector? then test the the pins inside the wiring connector for voltage when brakes etc are applied.

 

as for your original question...fuse 107 will not affect brakes and the such. it just provides a 20A 12 volt source to your 7 pin connector. rv battery charge etc.

unless it has shorted out with another wire in the harness...i would think that when you replace it if the short is still present it will blow very quick.

 

had a problem like that and it was where harness plugs into rear of 7 pin connector had corosion,I never knew the plug was there til I got to checking it out

 

There are relay's for the trailer connector(s) also. You might want to check them.

I have a 2004 F-250 service manual, and it's confusing. It shows two relay's (one left, one right) in Auxiliary Relay Box 4 and two in Auxiliary Relay Box 5. I dunno why it's showing 2 sets of relay's.

Relay box 5 is in the engine compartment on the drivers side fender all the way to the rear. It doesn't show where box 4 is.

And, of course, I couldn't say if any of it would be in the same place on an '05 F-550.