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On my 94 f150 I wanted to get rid of the 6 pin trailer adapter already installed on the truck when I bought it.
I bought a Hopkins 4pin/7pin plugin and wired it in. There was a 4 pin plugin from the factory back at the bumper. Then the previous owner had wired in trailer brakes with a 12v constant. Ground was there so connected to that
All that’s left is reverse. Nothing was there for that. I thought about tapping into the tail lights but I’ve read a couple places that I need a relay for reverse. Can someone clarify? Do I need a relay or do I just tap into the reverse wire from the tail lights?
Last edited by dualsportguy; Apr 19, 2021 at 07:55 PM.
@2dwoods Thanks, more or less my thoughts as well.
I read up on another post. Looks like it's all wired up from the factory possibly but the previous owner didn't know? Unsure. I'll post photos at some point but at the rear there is a factory harness with two plugs that plug into a 4 wire trailer outlet. I plugged into that.
I believe those two plugs disconnect and Curt or another towing company makes a 7/4pin plug that wires right into that harness. But I don't believe I have the fuse panel for the trailer under the hood though. The trailer brake controller plugs into a plug under the ash tray.
The previous owner ran a two wire line, one connected to the 12v constant and the other to the brake controller.
Based on what I read in another post, I should be able to get the harness that plugs into the factory plugs in the rear (unless I'm wrong) and move that wire from the brake controller thats in that 2 wire strand into the plug that plugs into the factory plug under the ashtray. Assuming that's all correct, I wouldn't need the 2 wire strand and everything would work, including the reverse wire as it's all in that harness from the factory.
On my 94 f150 I wanted to get rid of the 6 pin trailer adapter already installed on the truck when I bought it.
I bought a Hopkins 4pin/7pin plugin and wired it in. There was a 4 pin plugin from the factory back at the bumper. Then the previous owner had wired in trailer brakes with a 12v constant. Ground was there so connected to that
All that’s left is reverse. Nothing was there for that. I thought about tapping into the tail lights but I’ve read a couple places that I need a relay for reverse. Can someone clarify? Do I need a relay or do I just tap into the reverse wire from the tail lights?
Have you checked to see if there is not already a factory relay? I would think there is, but, I don't know for sure.
If you don't have the extra relays near fuse box under the hood, you don't have factory tow package:
Mine had the relays, but missing harness from plugs back to trailer plug. Also, mine had factory tow/trailer package, with relays, and with under dash plug for brake controller, but the blue wire from brake controller to harness was missing.
@wwhite Thank you for that. I might be missing that fuse box. I'll check. Attached are the rear plugs and the plug under the dash.
If I am missing that fusebox, can I add it? Debating if I just leave things the way they are and hook the reverse wire to the tail lights reverse wire light or if I switch it over to the factory trailer wiring... Assuming I have it all or if I want to add it.
Yeah, so, I had the same plug at the rear of my truck, not sure if its stock or aftermarket.
I hate splicing stuff.
What I ended up doing, was finding a 7-pin harness at the wreckers, took all that wiring, ran it from rear plug, al the way to firewall.
The blue wire I'm talking about was actually missing from the firewall to trailer plug, under dash to firewall was OK.
Here is a picture of how I modified my under hood plugs, blue wire from brake controller to plugs. I'll try and get a picture of my whole setup, it is currently removed.
I can understand why some would recommend a relay if you don't have one already. It's not like two more backup lamps add that much load to the circuit, but between the two bulbs, extra connectors and potentially a LOT longer wires, the added load might be considered borderline for the factory backup lamp switch.
Not sure what your year uses for a switch, but I would expect it to be part of the neutral-safety switch, or "range switch perhaps(?) and if one of the latter and on the side of the transmission with about a bazillion wires going to it (not like the "good old days" of just 4 wires) I would not want to put more load on it than necessary. Big PITA to change and not inexpensive either probably.
Just my thoughts on the use of an additional relay for trailer stuff.
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