Trailer wiring ???

[FED 387]

Joe--same bulb for stop & turn & tail lites( 1157 bulb in it) bulb is in correctly too----the clearance lites (all of em) flash when you turn on either the turn signals or emergency flashers---the stop/tail on the trailer works but they are dim--the stop lite on the roof of the cab(2000 Ford Super Duty) flashes too---the clearance lites work great UNTIL you turn the turn signals on have not tried it with the brake pedal did not think of that---seems to me that there is a ground wire thru the plug ---maybe climb under the trailer see where it ends up and if the ground there is bad to clean it off or drill a new hole---well I'll look at it tonite--thanx for the ideas will try a seberate battery test each circuit see if I have a bad wire someplace--thanx Comp387

[buzzinhalfdozen]

OK then you either have a bad ground or you're "feeding" back thru one of your rear lamps or sockets. Remove both rear TS stop lamp bulbs and try again, if it seems OK tryreinstalling1 bulb at a time to try and narrow it down to a particular socket. By removing both rear bulbs you're taking away the "feedback" path. Make sure the socket ground wires at the rear are connected as this could be your "feedback" path.Joe Your rear socket should have 3 wires 1 for tail 1 for TS stop 1 for ground

[Bob Verwold]

Joe, the trailer should ground the turn/stop lamp...........

[Bobby Brannon]

Do you have grease on your hitch ball. If you do you will need to ground the trailer. Then in trailer plug facing it about 5:00 is your ground.. Run wire from plug back to a good ground on trailer. Truck ground is at 7:00 make sure you have a good ground..



For Infro only

7 Way Plug Typical trailer wiring / position Knot on top at truck
Performance Trailer
Green is running lites / 11:00
Brown is right turn /3:00
Blue is brakes / 5:00
White is ground / 7:00
Red is left turn / 9:00
Black is a charging lite / 1:00
Yellow is back up / center

[buzzinhalfdozen]

Bob ,yes I know however if the ground for the pigtail or socket is not connected it may be trying to find another path to ground.depending on the bulb and socket design it may be grounding back thru the filament in the bulb hence backfeeding another circiut since the tail and turn lamps are on completely different circuits.I've even seen some people put a single contact I believe 1156 bulbs in dual contact sockets and cause the same sort of issue. Joe Oh and one other thing I see alot of ,when guys wire plugs a single stray wire touching the adjacent terminal can cause this issue. Sorry don't mean to confuse you just hard to diagnose not being there.I also neglected to ask, do the trailer brakes work? If so I doubt you have a grounding issue as thet use the most power of anything on the trailer.