It's possible.. see, all the communications for the car are run through the radio. The computer is connected to radio via "K" wire.

The K-wire is a data bus that goes between the hu and the ecu. Most everything in the newer cars are linked to the ecu, via a K-wire. If for example the right front woofer was disconnected, the ecu will know about it. If you connect a scan tool to the ecu and address the headunit, it will tell you that the right front woofer is disconnected. All the K-wire is is a communications path. When you hook up an aftermarket headunit, the K-wire is no longer necessary. If the K-wire is connected to anything, even to itself, it will cause problems for the ecu, and possibly damage the scan tool as well.

So to answer your question, it could very well void the warranty due to the fact that all communication for the car run through the radio. But I'm not 100% certain.

-Sphere11