I don't know what I am missing. I put an aftermarket spoiler on my 2008 TSX which went fine. When I went to hook up the LED I tapped into the power line for the third stoplight and a ground with clips to make sure the connection was correct. It worked fine. Then I soldered one LED wire to the power line and grounded the other and put on the power. The wires got hot and the insulation started smoking. Holy Cow! Turned off the power and cut the wires and there it sits. The existing third stoplight still works fine. I got another LED assembly since I think I probably fried the original one. Any ideas what went wrong? I don't want to fry the second LED and I don't want to pay someone to hook up a light if I can help it. Thanks

 

Do you have a multimeter? If not, you should invest in one if you plan on doing anything electrical. If you're not aware, a multimeter will allow you to measure electric potential, current, resistance etc. It will help you diagnose what's going on.

At first guess, I would think that the wires for your LED board are not the correct gauge to handle the current you're sending through them. I'm not sure why an aftermarket manufacturer would give you improperly sized wires for this application though.

Or, your soldered (+) is shorting. Are you sure your connections are properly insulated etc? Usually if you have a short, you'd just blow a fuse and not start melting wires so that's why I think your wires are not correctly sized.

Also, you might be better off tapping the ground wire from the third brake light rather than finding a new chassis ground. I'm not sure why you didn't do this since you tapped the power line from the third brake light.

 

I thought the same thing (blow a fuse before melting wire) but everything works and I can't find the third brakelight on any of the fuse lists. Anyway, when I get a meter, what do I look for on the wires I am tapping into? I assume 12 volts DC and 10 amps or so but I have never had one before and I'm not a mechanic or electrician. Also, I wired to a chassis ground because that's what I thought you should do. I'll try grounding through the other bulb wire. Also, the wire looks to be about the same as the wire leading to the existing bulb, so I think it is probably thick enough. Thanks

 

I would have a multimeter on-hand to measure the current through the LED board and separately (with the LED board detached), through the 3rd brake light. Off the top of my head, it should be way less than 10A. You could also test the resistance across the LED board and the resistance across the 3rd brake light (with bulb installed of course). All I can think of is that the LED board doesn't have the proper resistance and so connecting directly to a chassis ground is essentially just shy of an electrical short, melting the wires.

 

I was able to get the new LED working properly this weekend by grounding through the ground wire of the third brake light bulb. I got a multimeter and checked everything first before hooking up the LED. Based on that, I think your theory on grounding through the chassis was right. By the way, the first LED was totally trashed, wires at the circuit board were totally melted through and the circuit board was black. It could have been a disaster! Anyway, thanks for the help.

 

Glad you got it all figured out. I figured that was the problem. I've seen a bunch of people do this wiring various things to factory wiring. Just as a precaution, I'd check any brake light fuses etc. just in case you blew one out the other night.

Maybe you can recover the LED board by soldering the melted connections. You may have gotten lucky and only the connection fried and not the actual LED. If that's the case, you might be able to fix it.