05 Cobalt. Radio Installation Problems. Gauges Inop
Just tried out my new radio set up in my fiances 05 cobalt. It's a base model, no bose, no onstar. Used the metra wiring harness for cobalts. Didn't buy the $100 interface cause I was under the impression I didn't need it.
With everything hooked up, the gauges don't work, abs traction control and brake light are illuminated, and the mileage display is dashed. Also no sound comes from the radio but it turns on and works.
Do I need that interface after all?