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Aftermarket 3rd brake light problem

5.8K views 14 replies 4 participants last post by  BADLANDER  
#1 ·
Is there anything i am missing here- i just installed my new smoked led 3rd brake light and it does not work. Checked connections where wires for leds plug into bulb socket and everything seems fine. neither brake lights or cargo lights work. Is there a fuse i need to change that is too small and has blown? I put one of these on my f150 a year ago and never had a problem. If someone has installed one of these and could give me some help that would be great.
 
#3 ·
The cargo lights will come on when you hit the switch on the dash but thats the only time any of them work. The cruise control is not working now either. Impretty sure everything was workin before i tried to hook up the new light today. I have not driven the truck much since i got it and am not sure if the cruise was workin before the light switch. No one else has had any problems after installing one of these? I looked in the search but do not see much. one post said something about needing a load resistor-can someone confirm or explain this?
 
#7 ·
Brake switch, fuse, and load resistor are your best bets. Your cruise isn't working because you need the load resistor. A load resistor adds draw to the wire so your BCM will THINK there is a regular bulb there. Cause LEDs draw less load and the BCM THINKS you have burned out bulbs. So go get an LED resistor from Autozone and place it on the brake wire. And check the fuse in the block and replace if needed. And lastly check the brake switch will prolly be a dealership or mechanic shop trip, so do that last. Yes I had an LED third and yes I had the cruise problem but not the not working problem.
 
#8 ·
To be clear a resistor will change the voltage. What you need is a load equalizer, it doesn't change the voltage but it just makes the same load
 
#10 ·
Thanx for the help. I will try the old one again and make sure the new light is not defective. Then check to see if there is a fuse blown. If the brake switch was bad would the regular tail lights be out as well, because they are working fine. Also as i said i just got my truck and have not driven it much yet and i was wondering if the cargo lights are suppose to come on when the drivers door opens. I assume it should-all my other trucks have but i just have not noticed it yet. If it should it is not now, but will come on when you turn the cargo light switch on. Maybe the switch is on a different circuit/fuse. As far as the load equalizer goes is there a certain one i need (amps/volts)? I honestly do not even know what a load equalizer looks like-is it it something i just crimp in the brake wire or will i need to splice it in?
 
#11 ·
Yea, our cargo lights are done weird I think. Mine only come on if the dome is and you push the button. And below is a generic image of a load equalizer. They generally come with wire taps.

Image
 
#12 ·
What size load equalizer would i need for that? 6 ohm like used for led blinker or no-thought i read in a post on here u need 25ohm load equalizer. Ruby which did you use? Would i need to order this online or would autozone or another store have one?
 
#13 ·
Supermodulation would probably be able to enlighten as to the exact size. I personally never understood the ohm thing. Autozone might have the different sizes. But if not Autolumination.com definitely does. And I never actually put the equalizer on mine. Just switched them out with stock as well as the tails for long/trailering trips.
 
#14 ·
ok thanx for your help ruby! maybe if supermodulation reads this post he can help me out or i will pm him and ask which to use. Pretty sure it was the 25ohm. only 8.99 so worse case if it doesnt work im out 10 bucks. Id like to keep the aftermarket one in and have it work with the cruise so hopefully i can get it figured out.