No Park Lamps at Trailer Plug
 

2005 F250 quad cab 4x4 diesel
Edge Juice
4" turbo back straight exhaust
I am at a loss here I hope somebody can help me.
I went to college for electronics so I have a pretty good idea how to troubleshoot. I have no 12v at my trailer plug either the round or flat plug. Have both turn signals/brake lights. I found only one fuse for the trailer park lamps and it is not blown. Power on both sides of the fuse. I checked the wire about 3 foot before both plugs and still nothing. Worked fine just quit one day after I unhooked the trailer and didn't work next time I hooked up. If anyone can help me I would greatly appreciate it.
Thanks

RE: No Park Lamps at Trailer Plug
 

Load distribution side of the Trailer Tow Park Lamp Relay is through fuse F2.38/20amp in the CJB/central junction box.. Relay coil feed is through the BN wire off of the main light switch..Check for both 'hot at all times' (F2.38) and 'switched' 12v at the trailer tow park lamp relay connector.. Could be a bad relay if the fuse is good, and the connector proves out for switched/constant voltage.. If it were a ground point issue, chances are more than one trailer lamp control would be affected.. If a bad main light switch it would affect the vehicle lighting as well since the two circuits share a splice...

RE: No Park Lamps at Trailer Plug
 

Thanks Hayapower it is great advise I got a schmadic from ford and everything is just like you described but I can't find the relay for trailer park lamps I have looked everywhere it is not in the book and all non-used spots are still non-used. I hooked up to the trailer to make sure the trailer brakes work and everything works as normal except park lamps. 05 F250 do you know where the park lamp relay is located I am sure that is the problem. Still have power to both sides of my fuse. Hope someone can help me locate the relay

RE: No Park Lamps at Trailer Plug
 

Well,,, I guess I should have looked a little closer when look'n at the schematics.. The Trailer Tow Park Lamp relay is integrated into the CJB.. 'Non serviceable'..

I can send you the connector face/swith wire color/position so you can check for power distribution in/out of the CJB for the park lamps.. If the line out is dead,then the option would be a CJB replacement, or adding an aftermarket unit external to the CJB..

Sorry about the confusion...

RE: No Park Lamps at Trailer Plug
 

Thanks Hayapower
You have been alot of help solves the invisible relay......

RE: No Park Lamps at Trailer Plug
 

Sent you an email...

RE: No Park Lamps at Trailer Plug
 

Replaced the fuse box fixed my problem. Took the old one apart and found two relays soldered in place if you feel cofident enough replace those you will have your fix.....

I've got the opposite problem. All trailer lighting working, but the park lights on the truck are dead. How did you fix the fuse box?

check your fuses

Could be the VSM/Park lamp relay. I sent you some info that should help diagnose the cause..