HELP with wiring identification/instructions on 3rd brake light replacement on the 2002 Sport Trac

[dabenster]

Hello all...

I have a 2002 Explorer Sport Trac and I am wanting to replace my 3rd brake light above the cab. There are literally hundreds of replacement lights out there - most fitting a variety of Ford trucks and vehicles. I recently ordered one - see the link below:

Amazon product ASIN B0B4D3KM8V
I realized right away that I'd have to cut off the strange connector that the Chinese put on the lights - that part isn't the issue. The issue is that the wiring coming from the vehicle to the 3rd brake light is totally different (i.e. 2 black wires, 1 white wire, and 1 green wire). The wires coming from the truck do not fit the typical knowledge about electricity - i.e. red = hot - black/white = neutral - and green = ground.

I saw one video on YouTube that addresses this, however in following the person's instructions (using T-Taps) they did not work, and I'm now at wits end how to make everything work. I don't want to keep on old wiring harness in there - all I need are the wires, but which ones to attach to the ones on the replacement 3rd bake light is the 64,000 dollar question. Hope I'm making sense.

Any advice on where to look for proper instructions on this one?

Thanks in advance...

Ben Herrmann
Fuquay-Varina, NC

 

[J_C]

Maybe I missed it on the amazon product page you linked, but I don't see any wiring info for that. I saw a similar light on another amazon listing which looks like it has red, white, and black wires. I realize it would make too much sense to do it this way (lol) but I suspect the red is brake, white is cargo, and black is ground for both.

Anyway, on our vehicles, ground is (almost?) always black or black with some color stripe. On the earlier generation Explorers, the brake wire to the 3rd center light is dark green. From what I could find, it's still dark green your '02 if not lighter green.

Assuming your original light had white in it too for a cargo area light, then I'd hook that white wire up to the new light.

I don't know why there are two black ground wires. Possibly one of them goes to the tailgate latch/switch to turn it on if exterior lamps relay is on? Or does your replacement also have two black ground wires? If so then you can just swap the two back and forth to see which is which, or use a multimeter to see which connects to chassis ground with the tailgate closed, and that's the one for your brake lights.

If the replacement light has only one black ground wire, and the original used one of the two to ground out through the tailgate switch, then things get a bit trickier. In that case you might need to wire up a relay to make it work (or return the amazon light for something with two separate grounds for each circuit, OR if the light can be opened, you could probably cut a trace to make them not share the same ground and solder another new ground wire onto the white light portion to use as the 2nd ground connection for the cargo/bed white light. I hope this makes sense, I'm half guessing about this paragraph without a wiring diagram for the cargo/bed light circuit.

 

[dabenster]

Thanks so much for your reply! Let me clarify a bit, the wires coming from the truck are as follows:

Two all black
One black with a red strip on it
One Green

The aftermarket 3rd brake lights have just 3 wires - they are: Red, Black, and White.

This is my disconnect here. And the connectors are different also. All the new 3rd brake lights come with this connector (see photo below).

I obviously could not find the female connector that you would attach to the wires from the truck (once you figured them out), so it could easily plug into this connector as shown below. So the recommendation is to cut off the connector below and put T-Tap style connectors on the remaining wires. But again - from there, I have no idea what wires go to which.

 

[J_C]

The aftermarket light has no instructions indicating what the wires are?

Since it seems that you are going to hardware it rather than find a mating connector, what I'd do is pop the release tab in the connector to pull the wires out, then do a test with a cordless tool battery. If a 18V battery, only momentarily power them so they don't overheat, or a much longer run could be done with a 12V battery. Try red positive, black negative, which I was suggesting is probably the brake light, and white positive, black negative, the cargo/bed white lights.

Every diagram I looked at had a green wire for the vehicle factory brake light positive, and black wire for ground. If that's true, the remaining question is where the cargo/bed white lights are switched on, whether it is upstream on the positive lead, or downstream between the light and ground. Upstream should work with what you have, while downstream would need something more added.

Do you have a switch in the cab to turn the light on? If so, then I would assume a permanent ground and any 2nd switch just works in parallel.

 

[429CJ-3X2]

The way I read the Ford Wiring book,
green is for the 3rd brake light
black with pink stripe is for the cargo light
solid black are ground

Can't help with the wires in the aftermarket light

 

[oklagp1200r]

Thanks so much for your reply! Let me clarify a bit, the wires coming from the truck are as follows:







Two all black



One black with a red strip on it



One Green







The aftermarket 3rd brake lights have just 3 wires - they are: Red, Black, and White.







This is my disconnect here. And the connectors are different also. All the new 3rd brake lights come with this connector (see photo below).







I obviously could not find the female connector that you would attach to the wires from the truck (once you figured them out), so it could easily plug into this connector as shown below. So the recommendation is to cut off the connector below and put T-Tap style connectors on the remaining wires. But again - from there, I have no idea what wires go to which.



I would get a jumper wire and test each wire individually to see which bulbs light up! On the red and white wire since more than likely the 2 black wires are grounds.