Clear Tails- LED Bulbs wrong resistance, 3rd Brake light always on! | Ford Explorer Forums - Serious Explorations

  • Register Today It's free!

Clear Tails- LED Bulbs wrong resistance, 3rd Brake light always on!

Ok. Today I learned some important information for a VERY expensive price. For quite some time now, my 3rd brake light has chosen to stay on all the time- even when the car is off. So, I took it to the local Ford dealer and they thought it was the wiring. They replaced my tow/brake wiring and gave it back. Later that night, someone felt obligated to tell me "hey, your light is still on, you know." what the F%&@. So i took it back the next day, and they went back to work. They took my WHOLE interior apart and checked all the wiring and relays: under/inside the dash, inside the doors, rear quarters, liftgate, inside the taillights, trailer harness, etc etc- EVERYTHING. Then they decided to check what I had for bulbs in my clear tails. I use a set of 3157 Red LED bulbs for my brake lights. They replaced these with regular 3157 bulbs for experimental purposes and everything was back to normal- no more naughty 3rd brake light. The cause of this, they said, was that the LED bulbs had an improper resistance level in comparison to the stock incandescent 3157 bulb. The way the 3rd brake light works, is by a resistance module. when the resistance of the brake bulbs lessen (i.e. when you hit the brakes and the bulbs light up passing current through them) the module tells the 3rd brake light to come on. Since the LED bulbs had a lower resistance than stock, the module thought the brake lights were on all the time, thus keeping my 3rd brake light on all the time.

So, now that the problem has been discovered, and I paid my Ford dealer some hefty cash just for a lesson in bulb resistance and no fix, I need to find a solution. My first thing was, "ok- we'll just splice some resistors into the power leads to the bulbs." that won't work, because now you're limiting the power that the brake bulbs themselves see, and they won't light up properly.

SO I NEED HELP! hehe. Has anyone else had this problem using 3157 LED bulbs for your brake lights? If yes, what did you do to fix it? If no, what brand LED bulbs were you using?

THANKS!

Eric
 



Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!
.





I Can Defy,

Try running a separate wire from your brake light switch to the third brake light setup.

Run the wire separate from everything else, also run it without dressing thinks up first, just to see if it will work.
Leave enough wire when cutting the third brake light wiring to reverse the process if things don't work right. Make sure the Third Brake Light Module is separated from the new circuit.

If the separate wiring works OK, then try using your LEDs in the brake light locations and see what goes.
NOTE: Remember that the existing brake light switch wiring has to be connected for the main brake lights to work, SO if the new wiring works make sure you connect the old wiring and the new wiring for the switch together.

I think you have separate directionals, so this process should not effect them.

I have heard of the LEDs causing problems with the directionals because of low resistance but not brake light problems, interesting about the module thing, one for the books.

Make sure you get back to us on the forum and tell the forum everything you did, GOOD or BAD.

Good Luck, Take your time.


:usa: :chug: :ca:
 






CONFUSED!

:eek: ok, you confused me! do you have any type of diagram or way better detailed description of what i have to do? it sounds like it'd work in theory, i just wanna get it 110% before i go and cut wires and splice into stuff. thanks for the help!

Eric
 






hey there- wire in a resistor or two inline with the third brake light.
 






that would work, except that the led brake bulbs in the taillights slightly glow all the time as well. so does the "theft" light in the dash even when the truck is running because it is partly patched through the taillights. good idea though.

anyone else?

eric
 






I Can Defy,

Sorry about that - :chug:
Let me try to un-confuse things.

Try running a separate wire from your brake light switch to the third brake light setup.
New -((Usually under the dash connected to the brake pedal is a switch. This switch reacts to the brake pedal being depressed causing the brake lights to activate which also causes the third brake light to activate. So the thing to do is disconnect the wire that comes from this switch and run a wire from this switch to the third brake light, by-passing the special circuit for the third brake light).

Run the wire separate from everything else, also run it without dressing thinks up first, just to see if it will work.
New -((Try a wire directly connecting both the brake pedal switch and the wire that is attached to the third brake light first, before snaking it in a more permanent location. You may need to cut the wore coming out of the third brake light so you can attach the wire coming from the brake pedal switch).

Leave enough wire when cutting the third brake light wiring to reverse the process if things don't work right. Make sure the Third Brake Light Module is separated from the new circuit.
New -((Do not connect the wire coming from the brake pedal switch to the third brake light module, connect it directly to the third brake light itself).

Note: Remember that the existing brake light switch wiring has to be connected for the main brake lights to work, SO if the new wiring works make sure you connect the old wiring and the new wiring for the switch together.
New -(The original wire that is connected to the brake pedal switch has to be connected in order for the original main brake lights to work, not the third brake light).


I hope this helps, let me know what’s up...
 






sounds like it'd work...but:

will splicing into the brake switch effect the current the taillight brake bulbs receive?

and how owuld i run a new wire through the liftgate?

eric
 






Back
Top