Stereo Install Question

[xiii]

I want to install a JVC KW-AVX740 into my 2009 Yaris Sedan (Canada). On the back of the stock deck there are 4 different plug-ins. When I get the new harness for my car there will only be 2 plug-ins. Are there some wires that won't be connected on the new deck? (I'm new to this and couldn't find any info on this. Thanks)

Is there a tutorial that explains this?

[Kaykogi]

I believe the AUX panel is a separate plug that will not be used. I could be mistaken, but I think this is the case.