not so much melted.....but the plugs are a sort of rubber stuff, soft and flexible, on my 7 dollar gem the cargo light plugs are fine, but the center brake light plug is hard and crusty....like someone sat for a week solid with foot on the brake pedal....now it wont slip out of the hole to be able to change the bulb, and the bulb looks like one of those old time flash bulbs...the glass is even swelled on one side......im assuming there was a serious voltage spike when the donor truck was wrecked

 

Thanks for the pic F150XLT

@93MARKIII well my cargo light was also crusty but I managed to take out the bulb.

Here is the cargo lamp hole btw.

 

yea, on the 95 donor i got my $7 light from the areas where the clips for the screws are were dimpled so the clips fit flush with the sheet metal...... wonder if that makes a difference?.....

 

Would we be able to use those little clips for the new screw holes? I remember I saw one taken off at the junkyard but I did not notice the retainers. Does it have retainers?

 

You will want the newer 3rd brake light to sit flush or it will leak. It probably has to do with the way the housing is made. I bet that older light is open on the back so the clips don't interfere with it.

 

Convert cargo light to LED third brake light for OLDER pre '92 trucks





It is brighter than the factory tailights.

I'll post a second entry with detailed wiring instructions and a diagram.

Tools and supplies:
Phillips screwdriver
Soldering Iron or Soldering Gun
Solder
Tube of silicone
Two inches of Heat shrink tubing
Multimeter or continuity tester
Wire strippers or knife
Electrical tape

Parts:
LED bulb:Eagle Eye 5 Wide-Angle 180 degrees High-Powered 5 Watt Led + 4x super-powered SMT Leds RED 1156 (1/4 down the page) This bulb must be used because of its 180* light emission pattern, lighting the entire cargo lens and its extreme brightness.
1156 bulb socket with attached ground wire. There should be no prongs or protrusions on the sides.
15 feet of 18 gauge wire

If Cargo light function is to be maintained:
Additional Tools:
Drill with 1/8 bit
Optional parts:
(2) cheap LED 1156(W) or 3156(W) bulbs (White for backup light) The head of the bulb cannot be more than 1 inch in diameter. I used Jam Strait 1156W I bought at Autozone for about $5


A third, high center brake light is a good idea. It reduces accidents and saves lives. A study published 35 years ago in the “Journal of Applied Psychology” showed an accident reduction rate of over 60%. Those that were involved in rear end accidents reported over 61% fewer injuries. Today our trucks are in the small minority of vehicles without these lights. While two generations of drivers have entered the driving pool expecting to see these lights. The American Psychological Association estimates that for every $1.00 spent on these lights $3.18 is averted. Additionally the LEDs used in third brake lights illuminate quicker than a standard incandescent bulb, giving drivers behind you a few extra feet to stop.

The first set of instruction is to install a third brake light only. The second set is to replace the cargo light functionality. I can’t recall the last time I needed the cargo light. It was a waste of my time to install it in my truck.

Third brake light installation:
1) Remove cargo light from back of cab with Phillips screwdriver. As the 2 screws are removed the lens will drop loose. While the lens is removed clean it if needed.
2) Remove the driver’s door sill.
3) Feed the new 16 gauge wire through the cargo light hole in the back of the cab to the left. When the wire has reached the bottom, continue to feed it, routing it under the carpet and driver’s door sill to the fire wall at the break pedal.
4) Locate the stop lamp switch by the brake pedal. Using the continuity tester or multimeter, find the cold (lamp) side entering the brake switch. On some truck it is light green with a red stripe.
5) Splice (DO NOT CUT) the just located wire to the wire you just added together. If you do not know how to strip the wire, PROPERLY solder, or feel uncomfortable, use a scotch lock 3m connector instead.
6) Replace the door sill.
7) In the cargo light fixture, remove the bulb and socket. Do not allow the wire harness to fall into the hole in the cab wall.
8) From the front of the cargo light fixture, feed the wires and the socket, that you purchased, through the front of the fixture in to the hole the old socket was in. It should be a tight friction fit.
9) Using the continuity tester or multimeter, identify the ground wire in the original cargo light harness.
10) Splice the just located wire from the harness to the ground wire from the new socket. . If you do not know how to strip the wire, PROPERLY solder, or feel uncomfortable, use a scotch lock 3m connector instead.
11) Splice the other wire (switched) the positive wire from the new socket. . If you do not know how to strip the wire, PROPERLY solder, or feel uncomfortable, use a scotch lock 3m connector instead.
12) Seal the back of the socket with silicone.
13) Install the new LED bulb.
14) If you wish to add back the cargo light function, jump to the optional section below.
15) Reinstall the fixture.
16) Turn on the hazard flasher to check the lights!

Optional cargo light installation:
1) Drill a 1/8th inch hole through the back of the reflector half way between the center and the edge.
2) Separate the top disk from the two inexpensive 1156(W) bulbs. Be careful to leave the resistor and two leads attached.
3) Solder the two negative leads (were attached to the bulb’s “can”) together with three inches between and a tail lead of 6 inches extending from one.
4) Solder the two positive leads (were attached to the bulb’s center contact) together with three inches between and a tail lead of 6 inches extending from one.
5) Feed the two six inch leads through the drilled hole.
6) Route the positive and negative 3 inch leads around the center LED bulb. That bulb may need to be removed to route the wires than replaced.
7) Place the two LED disks on the reflector on either side of the center bulb, facing straight back (toward the tailgate) and held in place by a dab of silicone.
8) Splice the positive wire to the old switched cargo light lead.
9) Splice the negative lead to the cargo light ground wire (previously identified).
10) Test by headlamp switch to the brightest position.
11) Jump to step 15 above.

 

On the left there is a green wire with a red stripe. It is hot all the time. When the brake is pressed, the green wire is energized and the lights go on.

The third brake light wire must be spliced in on the green wire past the brake switch. This is the second VERTICAL wire in the schematic

If you have or might have a brake controller in the future, this is the place to splice it in also. This is the first VERTICAL wire. THis is the wire which would connect to the red wire on the brake controller.

The diode is a ten cent part that corrects a problem with using brake controllers on our trucks. When the hazard lights are on, they will pulse the trailer brake controller, causing the trailer brakes to engage with every hazard flash. This fix will stop that.

How does it work? The hazard flash mechanism and the brake lights are off the right side of the diagram. Electricity will travel either way on the green wire when the brakes are pressed or the hazard flashes. Either one will energize the trailer brake controller. A diode is like a one way valve that will only allow electricity to flow left to right in the diagram. This will stop the hazard pulse from getting to the trailer brake controller.

The wire colors are from 1989.

 

@lmd91343: excellent work and I really appreciate all that info and your time.

+1 to you

@TexasGuy001: yeah they don't interfere because of how the housing is made.

 

Thanks! .

 

I di the 3rd brake light mod to my 1980 14 years ago. While you are at the junk yard bring a piece of paper and a pencil. lay the paper over the hole after the light is removed. Mark your locations of the screw hole and the opening fo the light. Use the rear window OPENING as the refeence point, NOT the gasket( some gaskets are larger or smaller). I taped the papaer to my cab and used a center punch to locate the 2 mounting holes and the 4 conres for the light. I then pealed off the paped, drilled the 2 mounting holes with a 1/8 bit. A unibit in the middle of the light hole, then used a jig saw to open it up to the correct size.

A word of caution. the 3rd brake lights do have a tendancy to metle the housing so be aware of that

 

I am on the safe side because the housing I saw was not melted. What would be a good thing to do to prevent future melting?

 

i just skimmed through all these posts so i dont know is someone has said this but

when i wired and routed my cab mounted off-road light wires i took them into the cargo light

then with the back drivers side cab molding removed there is a hole made into the cab. i ran my wires to there then jumped them into the molding that runs over the door.

from there i ran it down the a-pillar and under the dash. i dont know about any of yalls trucks but my truck has a small hole with some kind of rubber sealer around it in the firewall.

from there it should be no problem to hide the wires under the hood and tie them into the existing brake lines that run back to the tailights



sorry if someone said all this already but i didnt feel like reading all the posts put up lol

 

Mine actually has a pre-drilled hole inside the cab that leads to the cargo light. How cool is that. Mine also has a bunch of those rubber thingys on the firewall. It should be a fairly easy project with a little cutting involved but I haven't bought my donor third-brake light. Anyways this topic is helping other persons who want to do this conversion. After all it is a cool mod to do.

 

haha i dont really want to do the conversion i just doesnt interest me. i just felt like putting my two cents in haha.

what i really need to do is figure out why even with a new bulb my cargo light wont turn on lol

 

Really... well that' odd. Did you pull the wire to hard or something lol? Is the connector all toasty or is it good? Does your interior light come on?