Hello, folks. Joined just today to ask this question.

I have a '98 F150 that apparently didn't come with a tow package. The previous owner wired in a 6-pin plug for whatever reason. I just purchased a small trailer and need to figure where to wire in a 4-wire plug.

I cut off the 6-pin plug as it didn't seem to be working anyway. I found that there were only 3 wires hooked up to it. Brown, yellow and green. There was a white wire cut and hanging but not attached to anything. The other wires had been poorly spliced into a harness on the driver's side at the back corner. I removed the splices and taped everything in preparation for putting in the 4-wire plug. They were spliced into a yellow wire and what looked like a dark red wire in the darkness of the corner.

Now, I turn to you folks. What or where do I splice into for the plug? I can't find a good place to start looking. When I tried to use my test light on the plug where the original wires were spliced, I get no juice.....but my rear lights are working.

With that, I bow to what seem to be there experts here and await some education.

Thanks!

 

No bowing, we are all in the same boat of helping each other out. Someday I am sure you will help me out with something, or help someone, that helps someone, that helps me ( I call it good carma, or Kevin Spacey called it pay it forward ).

The 6 pin round ( guessing round, could be flat ) the white wire would indicate ground, maybe that is the reason it did not work.

The correct place to install the trailer tow harness, is in the factory connector for the seperate circuits for the trailer.
Take a look under the rear of the truck, driver's side frame rail for a large connector. Usualyl easier to see if you drop the spare tire :
It might be in this location ( this is where it is at on the '01-03 and close to the same for the '04+ MYs ):

If this is where the 6 pin was wired to, the lack of power ( if you were using the frame for ground ) could be from not having all the fuses & relays installed for the factory trailer tow adapter.

The 1997 Owners manual does a better job of explaining the EngineMini fuse panel, which contains one of the fuses for the trailer tow adapter ( when installed in the factory location ) :


EVTM pages for the 1998 Trailer Tow adapter and the fuses ( note the little box with engine fuse module, that is the picture posted above ).
https://www.f150online.com/galleries...028-161575.jpg

https://www.f150online.com/galleries...028-161574.jpg

So let us know if the plug was wired here ( sounds like it, the parking lamp wire is brown )

Here are the part numbers that a member listed for the one shown in the picture above. Maybe a trip to a local dealer with this thread in hand might get you the correct trailer tow adapter, and then pick up the relays required ?
https://www.f150online.com/forums/sh...ad.php?t=60922

Your call, this is the long way around it ( vs. using a hoppie that plugs into the factory lights, old school method ) if you want to get into this depth.

Again, no bowing, this is not Japan, they just own most of HI

 

Sorry, had to do it.

That's precisely why I came here. Excellent info and diagrams. I'll be looking at it this evening.

Below where the PO had installed the round (you were correct) 6-pin plug (in the license plate light hole), there's a flat piece of metal that looks like the mounting point for the original trailer plug. This might mean it was originally wired for the lights. I'll be looking into it further after work today.

I can't thank ya enough.

TexasWolf

 

Konnichi wa, ( I know everyone is a comedian. )

Taking a look at the color codes on 95-2 & 95-3 above, the colors look correct for the factory trailer tow being used for the 6 pin round.

Vehicle Wiring :
Left S/T = Light Green w/ Orange stripe
Right S/T = Orange w/ ligth blue stripe
Parking lamps = Brown
Ground = Black

7pin ( and 4 pin ) wiring :
Left S/T = Yellow
Right S/T = Dark Green
Parking lamps = Brown w/ White Stripe
Ground = white
Dark Blue = Brakes ( from ctrl'r )
Orange = Battery charge circuit

The color might have been off looking at where you did, or the thing was just wired wrong. If it looks as back as you said, there might be a few blown fuses for the trailer tow adapter ( owners manual list them, don't have them straight away ) or the fuses and relays were never installed. It is common for fuse #2 in the Engine Minifuse panel to be blown ( if they had a problem ) and not replaced on the '98s. The owners manual does not have the section from the 1997 manual ( posted above ) for some reason. Don't know why, the first time I went tracking down a non functioning S/T on a 1998, it was about 20 emails into the back and forth, before he found this just poking around.

Good luck and let us know what you find, and how you want to tackle it.

daijoobu ( I thought with the bowing, we were in Japan )

 

You could save yourself a LOT of trouble buy spending ~$10 at WM on a 6-pin-round to 4-pin-flat adapter plug. It's smaller than a lime so it's easy to toss in the glove box when not needed.

 

If the existing plug he had was working, I would have suggested the same.

The easiest way would be to pick up the harness with teh receptacle at a salvage yard or a dealership, lay under the truck, unplug the old garbage and plug in the new harness (and mount the bracket to the bumper, of course).

Assuming the fuses weren't blown, the lights should be up and running.

-Joe

 

I've got a 6-to-4 adapter that I got at UHaul once but we were having issues making work and I think it was due to the 6-pin plug not being wired properly. That's why I decided to just go with a 4-pin plug since I've had the truck for 4 years and have yet to pull anything with a 6-pin plug. Plus, the plug just looked "poopie" the way it was mounted. I can clean up the bumper area with the 4-pin plug but capping the plug and stuffing it inside the receiver hitch.

I have power to the back end in the wiring so the fuses are good. That's what confused me. This is complicated but I'll try to explain:

Using the existing wires tapped the way they were, I'd get running lights but either turn signal would result in both taillights on the trailer blinking dimly. When I disconnected the yellow and green wires they had spliced in, I lost power to the brown wire. If I put my test light on the existing green wire they'd tapped, I had no power. But if I put the test light on the existing green wire while the spliced yellow wire was connected to it's existing tapped wire, I had power in both. The white wire was never connected and I suspect I didn't need it since the trailer was grounded when it was hooked up to my truck. The trailer is brand new and the 4-pin connector they used has the white wire cut and not grounded to the trailer.


It's like the wires are wired in a circuit that I'm not used to. I've installed trailer lights in the past on 80's model trucks and I just tapped into the taillights and it was all good.

I'll have a go with it this evening and report the results. Thanks for all the info.

 

On my little trailer I HAD to ground to the trailer & the truck for the lights to work, so you might want to do that first.

 

I'm home and getting ready to go crawl underneath her now to see what I can find. I should have some answers shortly if my plug wires for the new plug aren't too short. Then it's another trip to Autozone.

 

Well, it's working.

Sscully, I couldn't find a connection like in the diagram so I'm thinking my truck was never wired for trailer lights.

So, in true redneck fashion, I pulled the taillight housing from the truck, found the wires I needed, found them in the harness by the driver's side rear, tapped them with good wire taps and got it working.

Thanks to all for the insight and information!

 

Well, that works also. Quick way to take a flat 4 extension and turn it into the trailer tow adapter.

Considering you are not using a round 7 pin, I would not think the trailer to be that large, and not draw that much power on the factory harness with lots of marker lights.

Think of it this way, up until I got my 2001, all my trailer tow adapters were the hoppy inline kits, with the brake and battery charger ckt run to the front in 10 AWG. That still works on my '95 that my friend bought from me. That was using a tandem axel Wells Cargo, with the christmas trees on it.

 

The trailer is a very simple 3-rail motorcycle trailer with two taillights on it. When I finally get a Wells Cargo, I'll actually wire in a good plug and take my time getting it wired in with a good 6 or 7 pin plug. I just needed the plug to work for now since I've got a pull happening right after the weekend and didn't have much time to work on the lights.

Regardless, I wish I'd found this forum a long time ago. It's amazing the wealth of information here.

Thanks again.

TW