I have a 1993 Ford F-250 with a 7.3 non turbo. I have no break lights the all green wire that goes to the connector that plugs into the switch has power when the connector is jumped. I checked the fuse with a test light while having the connector jumped with a wire and it was good I also pulled it out and looked at it all was good. While I had the fuse out I took my test light and touched both pieces of metal that the fuse plugs into one of them had power I even tried a different fuse. I do know it's not the connector itself. Where do I go from here? Thanks

 

I think the First suspect would be a bad brake light ground. Ford ground wires are supposed to always be BLACK. I don't have time to look up the location of the ground connection for the brake lights. (but I guess I will in a few minutes) My shop manual(s) are for 1987-1991 generation 8 and your truck is generation 9, produced from 1991-96 Lets hope the wiring is the same (should be close enough)

IS THIS TRUCK A FLARESIDE? (where the fenders stick out from the bed?) IF SO, The turn/stop lights are grounded AT THE SOCKET. I guess that means you have to pull the tail light assembly out and examine sockets and why there isn't a good ground.

I don't think that is what you have because each side would be independently grounded and both sides of yours are out, so lets look at the other case, a ground wire.

What I'm looking at (ground wiring) shows one or two splices by the licence plate lamp (wire). One says "with rear bumper only" probably means trucks with a regular pick-up bed rather than a flat bed. Whatever, just look for black wires spliced at that location, and make sure there is a good connection. Follow those black wires back to the tail lights and make sure there are no defects like a broken or frayed wire in between.

There is another splice in the tail light ground wire in the harness where the Front Fuel gauge Sender is also spliced into that harness. Just look for the wires coming from the Front Fuel tank Sender coming from the top of the tank, around to the back end of the tank and you'll see the splice location. That harness runs (along the frame rail) all the way back to the tail lights. You might get real lucky and fix a loose ground for a fuel sender and gauge that isn't working (if that is an issue)

NOW, the common ground connection for those wires is up in front under the hood. That ground connection (G801 in my book) is located on the Left Hand Inner Fender behind the Headlamp. Disconnect it clean it up so you have clean metal surfaces for the connection to provide a good ground and reconnect it.

You might want to use some dielectric grease on the ground connections to prevent corrosion. Some people do and I'm not sure about using it on a ground connection. I use it on plug connectors sometimes, especially those exposed to weather.

You can get it in tiny packets at parts store counters (usually on a small rack) for 99 cents.

If that's not it we'll have to look at positive wires and connectors and I am way too tired to even look at another drawing and there will be a number of those to look at.

Oh I forgot. Do you have trailer plugs wired in at the back or remnants of previous trailer plugs? That could be a source of a problem. What about an electric brake controller?

I'm too tired to go any further so I hope that correcting any defects in the ground wiring solves the problem.

 

First question for the OP:
Do you have turn signals?
If you do(on the rear), then grounding isn't the problem - the turn signals use the same filiment in the bulb.
If not, I'd be checking grounds and bulbs.

If the turn signals do work, the next thing to check is the multifunction switch - everything goes into it.
Look for the wire at the brake switch that is LG(light green?). You don't want the one with red strip.
Take that wire and run a piece of wire straight to a source of power. Do you get brake lights?
If so, check the brake switch.
if not, you'll probably want to pull apart the steering column and look for the switch - remember, the turn signals and brakes go through the same wire, so if the turn signals work but brakes don't... it's not the bulb or anything past that switch.

 

have had this problem. pull of steering wheel and inspect wiring. mine rubbed off insulation and shorted. little piece of tape & good to go.

 

yup I had a similar problem and the problem was within the column in the turn signal switch