03 F250 Trailer Light Problem

Maybe the trailer that doesn't work with the Ford has a ground problem. Maybe it grounds OK through the hitch on the Dodge, but isn't on the Ford. When hooked up, try running a wire from a bare spot on the trailer to a bare spot on the Ford.

Matt

99 V-10 Super Duty, Super Cab 4x4

I would suggest the same. Borrowed a 18` car hauler from a neighbor who also has it hooked to a Dodge and the lights worked fine. Put it on my Ford and the lights didn`t work or once in awhile when we could get them working they were dim and worked erratic. Ran a ground wire from the Ford and then to the trailer itself and it all worked like it should. Ended up making a permanent connection on his trailer and my truck with a wire and female/male butt connectors so I can just plug my ground in when I use the trailer. When not in use I just wrap it up under the truck. All my boat trailers and etc work just fine without it though.....

My 03 F250 trailer wiring is full float - does not use a frame ground, so if your trailer frame grounding has a rough/dirty connection to the ground wire of the 7-pole plug, nothing will work right. When I have that problem, I usually just tee-in a new wire from the

7-pole to the trailer frame.

Dave

Thanks.

Dave, who are you kidding? If you expect to get a negative connection to the battery, your 7 pin is grounded somewhere. Even if you run a wire all the way back to the negative terminal of the battery, it is still grounded. The only thing floating here is your BS.

His point was the trailer is grounded through the trailer hitch, not through the 7-pin, which can cause all sorts of problems.

• * * Matt Macchiarolo
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"Sudoxe" wrote : >

: : Dave, who are you kidding? If you expect to get a negative connection : to the battery, your 7 pin is grounded somewhere. Even if you run a : wire all the way back to the negative terminal of the battery, it is : still grounded. : Of course it is... but the brake light/wheel brake actuator sets are full electrical float - unless there's a problem elsewhere, they shouldn't be able to ground through the trailer hitch, only through the 7-pole plug. Been through this with 2 trailers and 2 different trucks in the last month. Ford folk say it's set up that way for the anti-lock section of the computer.

I've rewired that trailer several months ago. I never connected a ground wire going to the frame of the trailer. The ground for the electric brakes and the lights all come off the 7 way connector. On my dodge the ground for the 7 way connector is connected directly to the frame.

So I should run a wire from the ground off the 7 way connector on the trailer to the frame of the trailer? Or should I connect a wire from the 7 way ground on the truck to the frame of the truck?

I'm going to go dig my trailer out of the mud at the trailer park and try to fix the problem today.

Just a wire from the trailer side of the plug to the trailer frame will do the job.

Dave

connection

If you say so. However, if you look at the schematic, you will see that you are wrong. BTW, where did you come up with the phrase, "Full electrical float?" In order to have anything on the vehicle operate as you state, you would need to disconnect the ground side of the battery from the chassis and run a negative lead to all systems. You can't have it half and half as you would like us to believe.

"Sudoxe" wrote in In order to have anything on the vehicle operate as : you state, you would need to disconnect the ground side of the battery : from the chassis and run a negative lead to all systems. You can't have : it half and half as you would like us to believe. : : Naw... it's not that hard. Per service manual page 95-1, Aux Relay Box 5 item C1384 (left relay) and C1383 (right relay) use wire 20bk (wiring ground) off the 7 pin plug as the relay ground, and the ground wiring doesn't touch the frame in that particular circuit.

See, I never make this stuff up - I just look it up and pass it on, trying to help. For some reason, Ford decided to keep these 2 relays completely isolated

Sorry I didn't quote the service manual in my first response. Dave

Ultimately, both. (But if all of your lights and trailer brakes are running a seperate ground wire leading into the ground pin on the

7-wire, then you wouldn't need to "T" a wire in and run it directly to the frame. )

Matt

99 V-10 Super Duty, Super Cab 4x4

You are telling me that pin #7 doesn't touch ground? I'll bet if you check continuity between #7 and ground, it does touch ground. Try it and let me know what your meter shows.

isolated

Dave