Fordrocks689

99 f1 4.6l 2wd

I currently have the 4 plug pig tail.

I am looking at purchasing a car hauler, which has electric brakes and 7 prong plug, trailer dealer says I can just purchase a conversion for the plug difference, but I would need to hardwire for the electric brakes. He also said I might have the wires running next to my spare tire and I could splice in from there...

Could anyone chime in on this and give some insight on what is needed?

paker

It's been a while and I am not 100% sure. My 97 had the 4-pin trailer plug. As you said, there is a 9-wire connector near the spare tire. What you need is a different wire harness that plugs into the 9-wire connector and has the 7-pin plug. I got mine from a junkyard. Direct fit. I still have the old harness with 4-pin plug in the garage.

Fordrocks689

I didn't even think about that! That's a great idea thanks dude! I'm gunna look into that.

Fordrocks689

So I verified that I do have the grey plug under the dash next to the obd2 plug. I also checked the fuse box and although the relay is missing I can see that there are connectors for me to just place a relay in the spot... so last thing would be to replace the harness from the spare tire to the back bumper then... correct?

Raybz

The plug next to te ODB is where you plug in a Brake Controller. Under the bed near the spare is where the flat 4 or 7 pin connector plugs in. I don't remember if the relay is needed or not ( I THINK it's for 12v power to a power jack and or charge a battery for said jack/lighting). the BLUE wire is for the brakes, 0v - brakes not engaged 12V = brakes engaged.

R&TBabich

You will probably need the relay for the battery 12v wire.
The battery line is usually there to charge a trailer battery from the tow vehicle alternator while on the road.
The relay is engaged when the key is in Start or Run so the tow vehicle does not drain the trailer battery when off.
If the blue wire ever has 12v on it the trailer brakes will lock-up.
The voltage supplied by an electric brake controller usually ranges from .2v to 5v or so.
That's what the brake controller does, provides a variable voltage to the trailer brakes depending on how much braking is needed.

kd4gij

My 99 xl has the fuses and relays for trailer brakes and battery charge but I only have the 4 pin plug at this time

Fordrocks689

Let's say I wanted to buy the 7 prong plug brand new does anyone know what it's called?

A new harness to go from the spare tire plug to the rear bumper 7 prong

kd4gij

Go to e-trailer and look up the factory tow harness for your truck.

Fordrocks689

Thanks! All makes sense now. My truck has everything to get started I just need the wire harness and a brake controller now then it's trailer shopping I go!