wiring in a topper third brake light

[biggyJ]

Hey guys,

Looking for a bit of guidance or past experience.

I bought a used super pacific topper that comes with a third brake light prewired into the topper. I need to complete the wiring to get it going.

google knowledge has made it more cloudy than I thought it would be.

It has 3 wires, red, black and white which I believe means it has a a low and high setting.

I initially thought about wiring into the taillight, but was advised not to do this as it they may be voltage controlled and if there is draw it may indicate that the bulb or tailight is burnt out. That seems annoying.

So then I thought about splicing it into my trailering harness. It has both the 4 pin and round 7 pin sockets. I only use the 4 pin for my boat trailer, so thought I could wire in before the 7 pin connector.

Good idea?
Here is what I plan on connecting everything to.

Third Brake Light ---- > 7 pin connector wire

red ---> red wire positive terminal
black ----> blue trailer brakes (I think this should be the high output light)
white ---> brown wire tail/running lights (I think this should be the low output)


Does this seem right? Want to check before I go splicing in wires and make a mistake.

[X-Treme]

My guess would be that the third wire is a constant power or tail light feed for an interior light in the topper?

For the brake light, if you have a single brake light wire at the back (GM trucks do - taped to the harness - fed from the center high mount brake light), i'd use that. If you use the brake light feed from the 7 pin connector, it's going to work with whichever signal light you tie into also (the brake and signal are combined on a 7 way/4 way).

You will definitely need to get a wiring diagram for the topper, but my best guess is that:

Red - brake light feed
White - tail/batt feed for interior light
Black - ground

[overhere]

There is no 3rd or high mount tail light wire at back of truck you will have to run a wire from cab back or wire into 1 for the brake/ signal lights , 7 way only has ground , reverse, left , right, tail, batt +, electric brakes

And the 3 wires on topper is possibly a interior light brake light and a ground

[Dean2]

Every one of these I have seen installed at canopy shops was wired to to the tail light, usually drivers side. Does it have an interior light as well as the third brake light?

[biggyJ]

Here is the diagram I got today from the topper company.

No interior light.

[HyperMOA]

I agree with Dean and the wiring diagram is what I would expect. You will have 2 filaments, thus 2 power wires.

[Peace Meal Farm]

My advice is run the brake lamp wire right back to the brake switch. I have seen many people try to cheat and wire it to the stop/turn bulb at a tail lamp assembly. They wind up with a flashing high mount when indicating.

PM me if desired with your year/make/model. I am happy to provide truck-side wiring diagrams if needed.

[Dean2]

Originally Posted by Peace Meal Farm

My advice is run the brake lamp wire right back to the brake switch. I have seen many people try to cheat and wire it to the stop/turn bulb at a tail lamp assembly. They wind up with a flashing high mount when indicating.

PM me if desired with your year/make/model. I am happy to provide truck-side wiring diagrams if needed.

If they get a flashing third brake light when the signal light is on, they wired it wrong, unless it was a REALLY old vehicle that didn't come with a third brake light and had the same bulb for stop and signal..

[beerhunter]

If it is a newer Ford do not tie into the trailer harness. It will bring up a fault code. Anything older than 2020 you are OK.

The wiring diagram you have is accurate.

[Mayhem]

Do yourself a favor and hot-wire in a fused interior light while you're at it. Saves having to look for a flashlight or turn on the IGN.