With the LAN adapter I bought with my Pioneer unit, the whole thing was plug and play. I found the unit stays on once I stop and even take the key out on a timer or until I open the driver's side door, not the passenger side door. I did not have to run any extra power or other wires which was great.

 

On GM vehicles 2001 and up I use a Scosche GM-05 harness. you loose the door chime and have to find your own 12v switched power, but for under 10 bucks, an option.

 

I have a 2011 HHR which was a Fleet Vehicle so it had a Factory On Star delete order. So when you want to Install a aftermarket Stereo you have to use a LAN Adapter made by SCOSCHE . In My case I had to Use #GM13SR and a Steering Wheel Control Adapter in order to retain all the warning Chimes and Turn signal Sounds as well as The RAP Functions. If You don't use the proper adapters you will lose Low Fuel Indicator function
, Low oil Level Indications Seat Belt Warning and it will also effect most of the DIC readouts as well as the Headlight and Key Chimes. The other problem is the Check Engine Light will come on Showing a code that the radio is missing and the Vehicle Diagnostics will be effected as well. One Final Note is that there will be no 12 volt accessory power at the radio Harness.

I hope this helps anyone attempting Stereo Up Grades. It is Possible but it needs to be done in the correct Way.

 

I don't have a LAN adapter and all you lose is chime sounds and turn signal clicks. I used a RAP wire in the fusebox and my radio functions just as a factory unit would....All my DIC info is correct and warnings light up...Check engine light? Where did you get that from? There is more than one way to do this install "correct"..for my needs I didn't want to spend the money on unnecessary noises coming from the speakers.