I've gotten fed up with my Federal Signal units burning through LEDs every couple of months and decided to look for another solution for LED CHMSL. This is what I came up with.
18-5050 SMD LED Dome Light Bulb T10/BA9S/Festoon Red off Ebay
. Seller that I got mine from is snb331. *Note: this was originally authored in 2012. The LED technology was likely vastly improved since then so you are encouraged to look for a board that uses brighter diodes.
Get 3 of these units. They are $5.95 a pop. Each comes with 3M double sided tape pad as well as 3 different wiring connectors.
3 of these LED panels side by side fill out CHMSL housing perfectly. My pictures show 3 of them already joined together. I used included double sided tape to attach them to each other. As far as wiring goes, simply daisy chain the 3 together and solder the ends.
The actual process of making this is pretty simple. Remove your CHMSL. There are 2 Phillips screws on the side of the housing. Take them out and the housing comes off. Unplug the electrical connector and take the unit out of the car.
Remove that white piece that holds the bulbs. There are 2 tabs that you push to release the clips.
The housings are slightly different depending on the year of your car but for the most part the same. What you will need to do is dremel out the inner bulb housing. So, everything that I crossed out in red must be removed. I just used a pair of clippers and broke all the plastic out. Took me maybe 2 minutes.
I suggest leaving a small lip on the edge though. It will help support the led panel.
Test fitting the panel. As you can see it fits quite nicely.
Use this wiring connector. It plugs directly into your factory bulb socket. Make sure you plug it in correctly. LEDs are polarity sensitive. If you plugged it in and it doesn't work, rotate the connector.
As far as mounting the panel in the housing. I used same double side tape and just stuck it to the edges. It stays on there pretty firmly. If you are worried about it detaching with time you could always use some plastic epoxy to secure it in place.
I then used that same double sided tape to secure the bulb holder to the back side of the LED panel. Then reinstall the whole thing in the car using factory screws.
The next part is optional and not required unless all of your rear lights are LED. If you replaced all your tail lights with LEDs then your cruise control will no longer work after you do this mod. The cruise is somehow tied into the brake light system and if it doesn't see enough current drop it stops working. A safety feature I suppose.
I bought one of these load resistors from a local auto parts place. It's suppose to simulate a bulb. You can get them on Ebay as well pretty cheap. Just search for LED resistor.
Wire it to your brake light circuit before it connects to the CHMSL.
Because it's a resistor it will get hot after a while so I suggest mounting it to a metal part of the car. I attached mine to the bottom of the rear package tray.
Oh and finished product. This is with my 10% tint. It's quite a bit brighter with no tint.
Hope this will help you out. I will be putting both of my Federal Signal units for sale as well once I replace burned out LEDs.