I have a 1998 Ford Ranger XLT 2.5L 4x2 and a Glasstite cap, and I'd like to wire the third brake light with quick release connectors. The cap has an interior dome light and four wires in total coming out of it (red, red, red/black, black), with two wires going to the dome light (red, black) and two wires going to the 3rd brake light (red, black). My truck has separate brake (red), reverse (white), and blinker (amber) lights and I bought a wiring kit with quick connectors, so I'm hoping the job won't be too difficult. I don't have any experience doing car electrical work, however I do know how to splice and solder wires, and I have heat shrink to protect the wires. I also bought a quick connect wiring kit (American Technologies C90-907) and have other connectors that might work (computer power supply extensions with male/female connectors).

What would be the best way to wire the cap third brake light? I attached pictures of everything to help, and I can take more if necessary. Thanks in advance


Truck rear

Left rear taillight wires

Left rear brake light wires (red)

Left rear turn signal wires (amber)

Left rear backup light wires (white)

Interior dome light

Interior dome and 3rd brake light wires (2 wires each to brake light and dome light)

Cap wires (4 wires total - red, red, red/black, black)

C90-907 Wiring Kit package

Wiring Kit complete

Wiring Kit close

Wiring Kit separated connectors

Wiring Kit instructions

Computer/PC power supply extensions with connectors

 

The Light Green wire, NO STRIPE, on either tail light is the Brake light wire, you can tap that for the 3rd brake light on the canopy
So it would connect to the Red wire and Black wire is for a Ground
You can tap the the Black wire on the same tail light you use for green wire, as the Ground for BOTH 3rd brake light and Canopy light


Canopy light can be tricky but only for what you may want
Do you want it to be activated by the Dimmer wheel, like the dome light and cargo light?
Or do you want a separate switch in the cab to turn it on?

Or do you want a switch in the canopy to turn it on and off?
If this.........then should it be Key ON only power or full time power so you can turn this light on and off without turning on the key?
This can present a problem if you leave it on by mistake.....................dead battery, but its also way more convenient, lol


In any case I just use a 4 wire trailer wire connector as the disconnect, like this: https://encrypted-tbn1.gstatic.com/s...Z5paQ&usqp=CAE
They are cheap and kind of weather proof, use the 1 bare connector end on the Truck side wires, as it will get the weather when canopy is off

You only need 3 wires as both bulbs can share one Ground wire, so the bare connector wouldn't be used

 

Thanks. I'd like for the switch on the interior cap dome light to turn it on/off, and I would prefer that it be key-on only (not full-time power) so there is no chance of a dead battery. For the cap, there are four (4) total wires coming out in two pairs of two wires (solid red + red/black stripe wires, and solid red + solid black wires). I assume that the red/black stripe and solid black wires both get connected to the ground wire in the brake taillight? However there are three wires going to the truck brake taillight and two of them are solid black (other is light green). Which of these black wires should I tap into for the ground wire, and should I just connect both the red/black stripe and solid black wires from the cap to this wire? For the two solid red wires coming out of the cap, should I connect the solid red wire for the 3rd brake light to the light green wire from the brake taillight? For the second solid red wire coming out of the cap (I assume for the dome light power), how should I wire it so that it can be key-on only power? Would I need to splice it to another wire that only gets power when the key is on (ex. power wire from the amber taillight turn signal (green/orange stripe wire))?

Thanks again and sorry for my lack of knowledge, but I've never done this before and I know basically nothing about electrical work. thanks

 

"However there are three wires going to the truck brake taillight and two of them are solid black (other is light green)"

On the tail light bulb socket the Light Green Brake light wire is with a BROWN wire(center), and a Black wire, brown wire is the Parking light, black is the Ground

Get a 9volt battery and test that "red/black wire" to the canopy, see if it IS a Ground wire, 9v battery should make brake light or canopy light come on enough to see it

If it is the Ground for one of the bulbs then:
Canopies Black and red/black to Fords Black wire on tail light

Red/white wire to Fords light Green wire, your observation that is the 3rd brake light wire, you can fuse this wire, 5 amp as suggested, as close to tail light as practical

Red wire will need to run to the engine fuse box, or into the cab fuse box, which ever is easier for you
There are several "Key ON" fuses in either fuse box you can tap into
There is nothing at the rear of the truck with "key on" power

You can go here and download your 1998 owners ,manual: https://www.ranger-forums.com/genera...1-models-3747/
It will have fuse layouts

Radio fuse in the cab is a good one to tap, has power in RUN and ACC both

You can tap a fuse using something like this:
Auto parts stores have these
You would pull out a fuse, put above in its place, put in the fuse that came out and the new 5amp fuse(double fuse holder), then connect red wire(in above picture) to the new wire you ran to the back of the truck



vehicles use DC voltage systems, + and -, positive and negative, although its not really "negative", lol, just 0 volts
cars use 12volts and 0volts, like a 9volt battery, 9v and 0v
0 volts is called a Ground in this type of system

A light bulb works by passing electricity thru it, it gets hot and starts to glow, lights up
If you hook a light bulb up to 12volts NOTHING happens
Because electricity can not "flow" thru the bulb, if you hook up 0 volts(ground) as well, then "current" can flow thru the bulb and light it up

Any thing electrical needs a higher voltage on one side so current can flow THRU IT

AC(alternating current) used in homes, use 110volts and 0 volts, but alternates + and - very fast, so current is flowing back and forth in the bulb(or motor or ??) and that makes it work, cut off either wire and NO FLOW, so no light or ??

If you hook up higher voltage TO lower voltage directly you will get what the light bulb does, but A LOT FASTER, wires HEATS UP and GLOWS, then smokes and MELTS, lol, its called a SHORT CIRCUIT because there is no device to slow the flow of electricity, no "throttle"
Like holding gas pedal down to the floor and seeing what happens................................lol

This is what you have to watch out for, shorts, and this is what a fuse is for, its a "device" like a light bulb, if there is a short, it will HEAT UP REAL FAST, and melt, which cuts off one wire, so no more short

 

[QUOTE=RonD;2156953
On the tail light bulb socket the Light Green Brake light wire is with [u]a BROWN wire(center), and a Black wire, brown wire is the Parking light, black is the Ground

Oops, sorry I didn't notice that.

Get a 9volt battery and test that "red/black wire" to the canopy, see if it IS a Ground wire, 9v battery should make brake light or canopy light come on enough to see it

If it is the Ground for one of the bulbs then: Canopies Black and red/black to Fords Black wire on tail light

Red/white wire to Fords light Green wire, your observation that is the 3rd brake light wire, you can fuse this wire, 5 amp as suggested, as close to tail light as practical

Red wire will need to run to the engine fuse box, or into the cab fuse box, which ever is easier for you
There are several "Key ON" fuses in either fuse box you can tap into
There is nothing at the rear of the truck with "key on" power

Don't the rear amber turn signals only work with key-on power? If so, couldn't I just splice the canopy dome light power wire (red or red/white) into the rear amber turn signal power wire (green/orange wire) so that it only gets power when the key is on? If not, and I don't want to bother powering the dome light, would I only need to connect two wires from the canopy to power the canopy brake light (red + red/black or black)? thanks

 

I just tried touching all 4 canopy wires (separately) to a brand new 9V battery, but none of the bulbs turned on and the wires just got hot. Also I don't know if this helps, but one pair of canopy wires (solid red, solid black) are a heavier gauge (~16 stranded copper), and the other pair (solid red, red/black stripe) are a lighter gauge (~22 stranded aluminum). What do you think the problem could be?

 

If the wires are in pairs, two 16ga and two 22ga, then one pair is for brake light and other is for canopy light

They can share same ground

Odd about the 9v battery, yes it would warm up because of the watts/amps needed, but you just need to test it for a few seconds to see which set of wires is for which bulb
From the pictures you posted the 16ga look to be brake light and the 22ga the canopy light


Turn signal wires only have 12volts when they are on, so on, off, on, off, on, off, ect..................
so not a good choice for canopy light

You could use Reverse light wire, only has 12volt key on and when trans is in Reverse, which would be doable with manual trans, but not great for automatic, and Reverse lights would need to be on when using canopy light

There is no 12volt wire at rear of any vehicle that suits a canopy light
Unless its was wired for travel trailer use, which was not really a Ranger use

 

What do you think that I should do next to determine which wires go to the canopy brake light, since the 9V battery didn't work? Also if I don't want to bother powering the dome light, would I only need to connect one pair of wires from the canopy to power the canopy brake light (solid red + red/black or black) to the truck rear brake light (green and black wires)? Thanks again

 

The larger gauge wires are for the canopy brake light, you can see it in your pictures, picture #7

So yes, connect those 2 wires to the green and black truck wires

 

Other than the 9V battery trick and connecting the canopy wires to the green and black truck wires, is there a way to test if the led brake light itself is still working? I don't want to connect all the wires just to find out that the brake light itself needs to be replaced. Today I unscrewed the 3rd brake light assembly from inside the cap and the led light strip was loose from its seating in the brake light. All of the wire soldering connections to the led light strip seem to be intact, but I still can't tell if it's broken or not. Tomorrow I'll unscrew along the inside of the canopy window to get access to the full lengths of wires that connect to the 3rd brake light and dome light, and see if there are any obvious problems. After I do that, should I try the 9V battery again directly with the wires that are connected directly to the led brake light strip, and if it still doesn't light up, look into replacing the light strip itself? Or is there another test that I could do to see if the led light strip itself still works? I don't even know how I would replace it or if the part is even available anywhere.

I'll try to take some pictures tomorrow to better show what I'm talking about, and thanks again for all your help.

 

You can test the LED light strip when its out using the 9v battery

LEDs may need + and - polarity matched, while regular 12volt bulbs do not

So match up + to + on any LEDs, strips or "bulb" type, they will be clearly labelled if + and - matters, and 9v battery is also clearly labelled + and -

 

I'm not sure that I understand how to test the led brake light strip itself. Do you mean to touch the red (+) wire that is soldered directly to the led strip to the + on the 9V battery, and also touch the black (-) wire to the - of the 9V battery? If that doesn't make the strip light up, what would you suggest that I do? Is it possible to just replace the led light strip inside the 3rd brake light?

Cap dome light

Cap dome light removed - 2 wires going to the brake light, 2 wires going to the dome light

Cap dome removed and brake light wires

 

Yes to the battery test, exactly as you described, if it doesn't light up then there may be a problem with the strip.......................or your 9v battery is dead, lol

 

One more question about the cap brake light. Is it usually only connected to the brake light wire (green) so that it only turns on when the brake is applied, or can it be connected to both the green and brown wires so that it functions as a third parking light? Is it best to wire it to be a third parking light, or should I just connect it to the green wire only? thanks

 

Brake light only

 

Thanks for all the help, I'm very happy with how it turned out.

 

Hey you got lights, good work

Thanks for the follow up and picture