I recently installed an aftermarket radio in my 2006 HHR. We hard wired it in because I couldn't find a harness for my car. When I went to test the radio it wouldn't come on at first but finally did. After driving a bit my guages flickered off and back on pretty quick. This was at night so the entire cluster just turned off and back on along with the radio. The next day my radio didn't work at all until I unplugged and plugged it back in and then my guages stopped working completely. My radio worked though. Now if I unplug my radio my guages work. But they stop responding once I plug the radio back in and start the car

 

Seems you tapped into the wrong wire for power or ground, look in the Crutchfield website for the correct GM interface . They have the correct wire harness adapters

 

The OE radio harness does not have a switched power wire; it is controlled by a digital signal from the BCM. The chimes for open door and key in are played by the radio from a digital signal from the BCM.

The correct GMLAN adapter takes care of those problems plug and pay. There is also an adapter if you want steering wheel controls.

Switched power can be had from any of the unused fuses on the BCM. The BCM is the inside fuse box below the radio.

 

Check them out….

https://www.crutchfield.com/m_266150/Car-Stereos.html