Bought a used 2008 Lancer ES, it already had an aftermarket radio installed. Problem was the touchscreen wasn't properly working, so I ordered a Boss Audio one off Amazon and installed and works great. Only thing I can't figure out is how to hook up the steering wheel controls for volume and phone and all. The head unit has 3 wires that are supposed to be for this, a black (ground) a brown (key1) and a redish (key2). Forgive me because I am slightly color blind. But I'd like to be able to hook it up without spending the extra money on a stereo control interface. I just can't seem to find anything online about key1 and key2 wires and where they would connect to anything. I know the easiest way is to bite the bullet and get the interface, but im on a budget. Any help would be appreciated.

 

Was it working with the previous aftermarket radio? If it was, it should have already had an SWC (steering wheel control) interface. You have to have a SWC interface, it's the only way to make it work that I'm aware of.

The wiring may be different, but on my 2014 Evo, the harness that connects to the factory radio with the steering wheel controls is not used, except for two wires. One is for ground, and the other I assume is the actual SWC.

The ground wire is grounded to the chassis, and the SWC wire is hooked to a aftermarket SWC device, usually a PAC or metra. This is how a shop I used did it.

I have since removed my aftermarket radio and replaced it with a stock nav unit, that's how I know all this (I've had it apart more than once). The aftermarket SWC has be be programmed. It's a little tricky but can be done. The programming sequence was different for my car than what the manual said.