I have a 1990 C4 and I just replaced the radio and speakers, but now the sys in the dash keeps flashing any ideas to why.
Thanks.

 

Welcome to the forum.
Sorry I don't think I can help you but what is a flashing sys mean?

 

you can google it. "Sys light flashing due to aftermarket stereo"
I've read about it in several forums. Had to do it myself on my 94. The system is looking for the correct radio and not finding it. There is a fix with two resistors and connecting them to two of the wires.