Codes, Codes, Codes… Have you noticed “SYS” intermittently showing up in your 1990-1996 Corvette’s speedometer display?  This means there is a trouble code stored in one of the on-board control modules.  When the 1990 Corvette debuted, GM introduced ECM (Engine Control Module) and CCM (Central Control Module) trouble codes.   In addition, ABS/ASR (Anti-lock Brake System/Acceleration … Continue reading C4 Diagnostic Trouble Codes