LED Brake and Backup Lights
 

Added LED brake and backup lights (dual-intensity 3157 Luxeon LEDs in red and white). Since they don't draw enough current (causes flasher to flash to fast), I had to add some 50 Watt 6 Ohm resistors to the brake / turn signal circuit. On the driver's side, this is the black and white w/ green stripe wires:

http://public.mvlan.net/content/Jeep...-lx2-40062.jpg

I didn't get a shot of the passenger side, but if I remember correctly, it's the black and white w/ yellowish stripe (kind of a really light lime green / yellow).

I tie-wrapped the resistors to the sheet metal to provide a good heat-sink.

The driver's side:

http://public.mvlan.net/content/Jeep...-lx2-40063.jpg

And passenger side:

http://public.mvlan.net/content/Jeep...-lx2-40065.jpg

js.

How did you determine the correct size for the resistor?
50 Watt seems high, but I have no clue. Planning on doing some of the same.

Nice work

It's not actually 50watts...
P=IV, V=IR
thus P=V^2/R = 12^2/6 = 144/6 = 24W

A 50w rated resister could theoretically HANDLE 50w, but otherwise means nothing.


Anyway, I'd be tempted to look into a new flasher rather than use resistors... resistors just waste power!

Pics of the finished lights?:thinking:

Sure - any idea where it is???

js.

A quick google found this:

h t t p : / /www.bikerhiway.com/universal-turn-signal-flasher-relay-p-294.html?zenid=4a8da37f0767b957afc2fc1e1bddea4a

No idea whether it would work though :)

edit: more:

h t t p://www.stu-offroad.com/electrical/led1/led-3.htm

h t t p://www.stu-offroad.com/electrical/led1/led-5.htm#q2

My problem is locating the flasher relay IN the Jeep. I've checked the parts manuals, etc., and there's no mention of it. If I could find the relay(s), then I would certainly prefer changing it/them than using heat-generating resistors.

js.

The flasher for the jeep is part of the main ECU. You will hear the flashing sound coming from the gage cluster itself. The sound is generated from a speaker in the cluster itself (not from a flasher unit like older cars) So if your lights would ever stop flashing you will have to replace the entire main ECU!:eek2:

You are correct the resistors defeat the purpose of installing LEDS to reduce power usage. The resistors use the remaining current and voltage by expelling heat. (wasted energy)

I have replaced all the bulbs in the JK with LEDS besides the headlights and fogs which are 35V HID's instead of the 55/75 Halogen bulbs. So I to have a fast flash but you actually get used to it after a while. I don't even notice now unless the subject is brought up.

Aha! That would explain why I didn't turn up anything in my search! Thanks for the info. A bit of a shame though... Hm. So if the flashing feature is part of the ECU, maybe the ECU could be 'fixed' using the OBDII port? Perhaps something to watch / wish for in the future? :thinking:

js.

I wonder if Chrysler could reprogram the ECU to provide less power???:thinking: