West Coast

My Ford dump truck has a 7 pin trailer plug. All lights work through my trailer plug except brake lights. The left and right turn signal do not carry the brake light signal. The plug has a wire for the brake lights but the PO installed in the center pin which is not correct. So what do I do with the single brake light wire? Turn signal and brake lights should be on the same signal from the diagrams I have looked at. But if I tied the single brake wire into the turn/signal light spot wouldn't the brake wire cause a back feed through the turn signal wire?
http://www.google.com/imgres?imgurl=...9QEwAQ&dur=336

chaikwa

That's wired like a semi-trailer most likely, with the brake lights separate from the turn signals. If you're trying to hook up to a conventional trailer you'll need to get a trailer light converter.

Like this: http://www.curtmfg.com/part/55177

West Coast

chaikwa I am trying to hook it up to a 7 truck to a 7 pin trailer plug. Not 4 flat. The 7 pin wiring harness is not tied in to the rear tailights. But goes much farther up the frame rail towards the cab. So there must be junction the PO tapped the trucks 7 pin into. Just strange to me that the turn signals in the 7 pin on the truck side do not fire for the brake lights like it should. The trucks taillights have one bulb for both turn signal/stop lights. So the 7 pin truck plug should be wired the same.

chaikwa

Ahh, NOW I see. I misunderstood. Sorry 'bout that.

Try sending a PM to admin Hvytrkmech. He's real good with this stuff!

torquefan

Possibly the previous owner got confused and tapped into the front signal lights to feed the 7 pin connector instead of the rear ones. The repair may be as simple as eliminating whatever feeds the signal light circuits into the 7 pin, and feeding them directly from the rear signal/brake circuits.

West Coast

Torgue thanks for the suggestion. I will look into that tomorrow.

Hvytrkmech

Does the truck have air brakes?

West Coast

Hi Hvy,

Yes the truck does have air brakes.

Hvytrkmech

I should have asked this prior. What does the directional switch look like? Does it look like a regular pickup truck turn signal lever or does it look like a larger chrome lever with a metal under pull for the flashers?

This info will define wether or not the system us a dual split system.

West Coast

Chrome switch with pull out flashers.

Hvytrkmech

Dang man, your not in a hurry to fix it. Lol

It is a dual plug system, there are most likely 2 separate wiring harnesses for the lighting on the truck. One will most likely be a 4 way flat and the other a 7 way run together to the back of the truck. In some instances, dependent upon how the truck was ordered the 7 way will not be run from the cab to the rear but there will be a junction block in the cab, most likely behind the passenger seat on the rear wall under the carpet and a plastic cover. Look under the cab at the rear for where the wiring harness enters.

Does the truck have a 7 way plug through the rear of the cab on the drivers side?

This is what stinks about Ford medium and heavy trucks, none are built the same.

Post back, we're getting closer

West Coast

Sorry man. Working 14 hours a day. 7 days a week. I don't drive my truck much. So it's not a priority. But I did post the wrong info. It has the stock turn signal on the column. Not the big chrome one and pull out flashers.