Thanks!
I think this is the perfect place for those pix!

 

 

I was so glad to find all these pics in this old thread......

 

I know that bumping old threads is frowned upon around here, but the last post in this thread was less than 2 years ago, so in the name of one-stop shopping, I will risk the consequences and post here.

I keep both adding to and crossing things off of the list of things wrong with my newly purchased 2009 Base H3.

I kinda suspected that my 3rd Brake Light (CHMSL, or CHiMSL) was not working. Last night, I finally checked... Sure enough, no CHMSL.

Like others, I decided to attempt to re-construct mine instead of buying a used part or an after market part -- about $100 either way. I'm an electronics geek, and I knew I could do better for a lot less.

What follows is the specific steps I did -- in detail, with comments and pictures along the way.

• Remove the tool access panel on the rear door
• Remove the rear door panel. Start from the inside, and pull the plastic clips out. These clips are just plastic pegs, and come out by hand with little chance of damage if done carefully.
• Begin removing the upper window trim by pulling on the points that are held in with the black plastic pegs only (Bottom).
• To remove the rest of the panel, a trim tool or similar is required. With the bottom loose, you can peer in the side and see where the metal clips are.

I had couldn't find my set of plastic trim tools so I carefully used a small metal pry tool and a rag to prevent damaging the paint. Make sure you get under the little tab on the metal clip, and don't break the peg that it is attached to. Mine seemed fine, but others have reported brittle and easily broken trim panels. When done right, each point releases easily, and the clips stay on the trim panel, and not in the door.

• Continue around each side until you release the top 2 just one either side of the CHMSL.
• I recommend not attempting to disconnect the defroster wires from the glass. I am too afraid of them breaking. Instead, release the wire from the plastic trim for both the rear defroster and the CHMSL.
• Demate (that's aerospace talk for "Disconnect") the connector from the CHMSL, and remove the panel from the vehicle. There's a tiny release button for the connector underneath.
• Remove the CHMSL from the trim (2 black Phillips screws)

My CHMSL was in really bad shape. There was one LED, a capacitor, and some broken plastic loose in the trim panel when I removed the CHMSL. The part of the circuit that remained (a printed circuit built directly on the heat sink, no PC board) was badly corroded. I couldn't even save the connector.



If GM wants to build the circuit this way, they really need to conformal coat it at the very minimum.

• Next, I "Cleaned Up" the circuit -- with an angle grinder.
• Make sure to grind / sand down to smooth, shiny metal. We will keep the functionality of the heat sink, and the LED strips will stick to a smooth surface better.

For those not familiar with these LED strips, they are designed to run on 12V (Make sure you get 12V strips) as long as they are cut every 3 LED's.

I used high brightness, high density LED strips for a total of 30 LED's! Do not buy cheap quality, but over priced LED strips at the local big box or auto parts store. I select LED strips with the specifications I want. If there is anyone in the Central Florida area that is interested, I will publish my highly recommended source.

Note that the strips in themselves are wired in parallel (That's why we can cut them as long as we cut in the designated places), so we must adhere to that and wire multiple strips in parallel regardless of the physical layout.






Here's a bench test:



Total draw in this configuration was 0.43 Amps, according to my bench power supply.

Note that I have applied marine sealant (3M 5200) to the ends. These LED strips are IP rated, but we need to seal the ends and the solder connections. The way I did this, it should not just be moisture resistant, but fully submersible.

I also had to build up the plastic where the heat sink is attached to the CHMSL housing. The screw holes were brittle and broken.




Here's a bench test after re-assembly. Note that the inner focusing lens is removed. I think it has a good pattern. Note that I had to use a JST connector since the original connector was corroded.

• Reassemble the CHMSL housing into the trim panel.
• Holding the trim panel up to the rear door, re-route the CHMSL and Rear Defroster wires in the little channels in the trim. Support the panel well so as not to yank the defroster tabs off the glass. (I'm really paranoid about this).
• If you disconnected the larger, white connector that carries both the CHMSL and defroster power, don't forget to re-connect it and push it together until it clicks.
• Carefully re-install all trim pieces.

Here's a picture of the final result:




Less than an hour's work (not counting an extended break while the marine caulk set up), and no new expenditure, as I had a full roll of the LED's, and the JST connectors on hand. I actually wasted a few inches of the LED roll, as I cut one strip in the wrong place.

 

 

Yes Hummerz... Well done to solve a common H3 problem avoid failing state inspection.