Where do I find the stop lamp wire for a topper?
 

I'm wiring my 97 F250 crew cab for a topper and I'm trying to find the wire for the high mount brake lamp. My wiring diagram says that there's a light green wire for the "cap center high mount stop lamp" and another light green wire for the "trailer stop lamps feed", both coming off "S240 (main harn. behind left side of dash". But I'm not finding any loose light green wires under the dash, and I wouldn't really expect that I'd need to run wires from inside the cab any way. If I remember corectly my '95 had a light green wire under the hood (I think near the master cylinder) and my '07 and '02 trucks had a light green wire loose at the trailer harness, right in front of the rear bumper. So I'd expect to find it on this truck somewhere like that, but so far no luck. Any suggestions?

To wire your cap I'd would just tap into your trailor plug harness find the wire that feeds your brakes run a ground off frame and drill a hole to feed wires up into inside of your box put a rubber plug in the drilled hole punch your wires though and hook up

But the trailer plug harness doesn't have a brake light signal. It has one wire for right turn/right brake and another for left turn/left brake. If I use one of those I'll be one of those guys that has his stop lamp flashing with a turn signal.

Ford does have a stop lamp circuit (obviously) for the high mount stop lamp on the rear of the cab. And they have a wire from that circuit available for a topper. At least my wiring diagram says there's one and my last three Ford trucks have had one. So it should just be a matter of finding it.

There is a brake light wire in the cab that's hooked to the trailer brake controller. I could T off of that. But I'd rather not have to run a wire out of the cab when I'm pretty sure there's one more readily available.

I know what your getting at .I know there is a wire for the stop light hook up for a camper top too .On some trucks it was in the wire harness where the cab and box meet in the frame .On some trucks it seemed that the wire was closer to the bumper in the frame by gas tank.I had a camper top on my 95 F250yrs ago Can't recall for sure where that wire was but it was in one of the 2 places I mentioned.Ican look in my Chilton Manual,

just looked in book the wire diagram shows alt green wire wire in fuse box for brake switch but doesn;t show where it goes from there I guess get the test light out and look for that Lt green wire in the wire harness in the frame.Can't help you more on this ,I could check my truck in the morning.

I found it
 

It was tucked way up against the bottom of the bed sheet metal, just inside of the left frame rail at the very back of the bed. Pretty much where I first thought it would be, but it was kind of hidden by the wiring a previous owner had added for the license plate lights on an aftermarket bumper. Also the wire wasn't very green any more, but after wiping 16 years of crud off it looked like a good bet.

I just wired mine into the left turn, I may go hunt for that green wire to make it work properly.

Nothing Special good to hear you found it.

This should work for you. It hooks up at the taillights. No wires back to the cab are required.

I just bought a converter, works great.

Given a choice between paying $19.17 and hooking up 5 wires or hooking up one wire without having to buy a converter, I'll use the wire that Ford already provided, even if it took me a couple of trips under the truck to find it.

EXACTLY, that is a no brainer.

just wish my 04 ranger has a 3rd brake light wire at the back of the truck

I don't know Rangers, but I'm kind of surprised it doesn't. My '95, '97, '02 and '07 F-series all have (although the '95 was under the hood).

If there's a harness for a brake controller that would have a stop lamp signal too, but it'd be in the cab, not quite as convenient.

nope. no provisions for 3rd brake light or brake controller

Guys...
Other than needing to run some wire, you don't need to spend money on a converter or anything.
The brake light switch at the pedal has two green wires. One with power all the time, and one when you push the pedal. You tap into this when you add a brake controller when you don't have the harness also.


I thought it was cool that my 97 explorer had the converter already built in. Ford thought ahead on those I guess.