trailer wiring question
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trailer wiring question
I recently traded my 03 scab (w/ towing package) for an 04 screw (w/ towing package) and purchased a Prodigy brake controller for the 04. When I hook-up to my horse trailer, the interior trailer lights and loading lights don't work. All other lights work. Is there a connection I missed?
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The 7 pin round connector has an AUX pin. This can be used for backup lights on the trailer; rarely used, or for other things like lighting in the trailer. You might check to see if the center pin is hot when you need it. 
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Steina - yes, the lights worked with the 03 but I did not install the brake controller and the truck didn't need to be running for the lights to work. I think 05F250Fan is probably correct that the aux pin is not hot. Thanks
05Fan - If the aux pin is not hot, is there much to making the connection? My experience with electric is basically changing a light bulb. Thanks
Chuck
05Fan - If the aux pin is not hot, is there much to making the connection? My experience with electric is basically changing a light bulb. Thanks
Chuck
Elder User
Joined: Apr 2004
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From: Wickenburg, AZ
There is a 12V "Battery Charge" Pin that is hot only when the key is on for 04s. It'll be denoted by "+" on the diagram.
There is actually a mini-diagram of what all the pins do that is cast right onto the flip-up cover if you've got the same factory one that's on my 04 F350 with the Tow package.
There is actually a mini-diagram of what all the pins do that is cast right onto the flip-up cover if you've got the same factory one that's on my 04 F350 with the Tow package.
CO River Rat
Joined: Feb 2004
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From: Lake Havasu City AZ
CJS51 -
Normally, no pin is hot on a 7-pin connector when the key & lights are off; I'm not sure how your '03 was wired to run the trailer's interior/loading lights without the key/engine being on. You need to check the trailer's 7-pin connector to see what pin powers those lights. Do the electric brakes work OK, now that you've installed the Prodigy? The "Aux" (center) pin is hot only when the key is on and gear selector is in Reverse.
Steve
Normally, no pin is hot on a 7-pin connector when the key & lights are off; I'm not sure how your '03 was wired to run the trailer's interior/loading lights without the key/engine being on. You need to check the trailer's 7-pin connector to see what pin powers those lights. Do the electric brakes work OK, now that you've installed the Prodigy? The "Aux" (center) pin is hot only when the key is on and gear selector is in Reverse.
Steve
Senior User
Joined: Feb 2004
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From: Kansas City
The seven pins should be, clockwise from top
Aux power - to charge breakaway battery,
right turn
Elec brakes
ground
left turn
Tail/running
backup - Center
(brake lights consist of lt and rt together)
You might have blown your aux power fuse. My '96 has seperate fuses for the trlr aux, trlr backup, and trlr lights in the engine fuse box. My truck didn't have a fuse installed for trailer lights the first time I tried to use it. Have you checked your owners manual for fuses or relays.
Aux power - to charge breakaway battery,
right turn
Elec brakes
ground
left turn
Tail/running
backup - Center
(brake lights consist of lt and rt together)
You might have blown your aux power fuse. My '96 has seperate fuses for the trlr aux, trlr backup, and trlr lights in the engine fuse box. My truck didn't have a fuse installed for trailer lights the first time I tried to use it. Have you checked your owners manual for fuses or relays.
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Senior User
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From: 39 24'34.8" N 88 47'51" W
On my 05 no pins are hot unless the ignition is on. The center pin only with the truck in reverse. On my last truck (98 Chev) the center pin was hot all the time. This was nice for my inside trailer lights. I am currently thinking of changing my 05 F250 to be the same way.
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Brett Foote
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From: Alaska
None of the pins should be hot without the key or lights on. If you got the truck used, then the PO may have wired it different.
I would concider adding a batt to the trailer. Run the lights off that and charge with AUX power pin as opposed to wiring the truck for a constant hot lead. Then you could use those lights when ever and not worry about things like:
Having truck hooked to trailer.
Accidently locking keys in truck.
Killing the main batteries in truck.
Just a thought you might be interested in.
I would concider adding a batt to the trailer. Run the lights off that and charge with AUX power pin as opposed to wiring the truck for a constant hot lead. Then you could use those lights when ever and not worry about things like:
Having truck hooked to trailer.
Accidently locking keys in truck.
Killing the main batteries in truck.
Just a thought you might be interested in.
Fleet Mechanic
Joined: Oct 2004
Posts: 1,496
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From: Simpsonville, KY
try turning on the headlights... many trailers use the running light lead to power interier lights. Good luck with the exterier ones, I have never seen or used a horse trailer with exterier lights that worked, and I tow/work around LOTS.
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Sorry for the delay. With holiday's & winter storm I haven't had a chance to look into it yet. Probably will this weekend and will post any results. Thanks and Happy Holidays
PS. 1)Tried the lights with the headlights on, didn't work 2) only exterior trailer lights work with the ignition off, but the head lights on
PS. 1)Tried the lights with the headlights on, didn't work 2) only exterior trailer lights work with the ignition off, but the head lights on
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Thanks for the thought grafekie. Yes all the internal lights (and the loading lights) are switched. I even checked the bulbs to ensure they didn't all blow! I'll have it figured out this weekend (hopefully).
Thanks
Chuck
Thanks
Chuck
Senior User
Joined: Jun 2004
Posts: 268
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From: 39 24'34.8" N 88 47'51" W
Originally Posted by Kaleo
None of the pins should be hot without the key or lights on. If you got the truck used, then the PO may have wired it different.
I would concider adding a batt to the trailer. Run the lights off that and charge with AUX power pin as opposed to wiring the truck for a constant hot lead. Then you could use those lights when ever and not worry about things like:
Having truck hooked to trailer.
Accidently locking keys in truck.
Killing the main batteries in truck.
Just a thought you might be interested in.
I would concider adding a batt to the trailer. Run the lights off that and charge with AUX power pin as opposed to wiring the truck for a constant hot lead. Then you could use those lights when ever and not worry about things like:
Having truck hooked to trailer.
Accidently locking keys in truck.
Killing the main batteries in truck.
Just a thought you might be interested in.
Thanks