I have wired up the garage door opener to the battery and high beam wire and it works great when the keys are in the ignition (position #2) but when I start the car the opener will no longer work. The only difference is that the voltage reading when the car is not started is 12V and some change and when the car is running its 14V and some change. The garage door opener apparently does not like this level of voltage. Is there any way to suppress the extra voltage or any other ideas of how to solve this?

 

You might try a different door opener remote. I use a keychain style one (uses a 12v battery) on my motorcycle. I removed the battery, soldiered wires to the battery contacts and hardwired it to my bike's headlight wiring. It doesn't have any trouble with the 14v voltage.

 

When I did this on my other car, I used a voltage regulator from Radio Shack (part #276-1771). This automatically lowers the voltage to 12V. Put it inline with the garage door opener and provide a ground to it and it does the rest.

 

I highly recommend installing the "Flash2Pass" system. I have installed this on my 2006 MCS Coupe and my wife's 2007 MCS Cabrio; works like a champ and there is no garage door opener visible.

http://www.f2ptechnologies.com/