Question for the wiring gurus
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Question for the wiring gurus
On my 93 F150 under the dash is a connector for a brake controller but my truck didn't have the 7way plug on the back. I have added a 7way socket, all the under hood relays & fuses. I have been unable to figure out where the red wire goes. The blue wire was easy to find & I made that connection. The green goes to the brake light switch. If anyone knows help me out here. This is the last piece of the puzzle. Thanks.
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I might not of explained myself properly. I have basically added a factory towing package to this truck by adding relays & fuses w/ the required wiring. I wanted to find which plug in the firewall & where in the plug the red wire was. The blue wire was in the firewall plug that went to the back of the truck but I had to add that wire on the outside of the firewall plug. If I can find where the red wire is I can do the same thing.
Posting Guru
Joined: Jul 2009
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From: Toledo, Ohio
I might not of explained myself properly. I have basically added a factory towing package to this truck by adding relays & fuses w/ the required wiring. I wanted to find which plug in the firewall & where in the plug the red wire was. The blue wire was in the firewall plug that went to the back of the truck but I had to add that wire on the outside of the firewall plug. If I can find where the red wire is I can do the same thing.
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Thanks for your help.
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Mountain Pass
Joined: Sep 2006
Posts: 116
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From: Harrisburg, Oregon
Subford, do these diagrams also apply to a '91 F250? I'm trying to undo the damage done by a previous owner who botched the installation of a brake controller (using household lamp cord, random wood screws, etc.). This evening after work I found that his blue brake controller wire was hooked directly from the battery's positive terminal to the the blue wire of the 7-pin socket, somehow missing the brake controller he had installed under the dashboard entirely. I would like to replicate the factory trailer wiring package in this diagram if it is appropriate to my year.
Thanks,
Scott
Thanks,
Scott
Fleet Owner
Joined: Aug 2005
Posts: 23,668
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From: Easton,Ks
I do not have a diagram of a 91 but I know the 91 does not have the engine compartment fuse box that is in the diagram above. The diagram above should be right for the 1992-1995 and maybe the 96 trucks. I do not know if the 91 had the plug installed under the dash as all 1992-1996 did.
The best I can do you is attach diagrams in PDF of the 1990 Trailer Adp.
I think a 1990 and 1991 are close if not the same.
The best I can do you is attach diagrams in PDF of the 1990 Trailer Adp.
I think a 1990 and 1991 are close if not the same.
Mountain Pass
Joined: Sep 2006
Posts: 116
Likes: 2
From: Harrisburg, Oregon
The 1990 diagram seems to match my truck in most particulars. It appears that the truck was built with the trailer harness as an option, but the previous owner didn't realize it and hacked the wiring to run his own wires. Thank you for this diagram. With it, I've got a pretty good idea how to repair my wiring.
Scott
Scott
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