Why does my TCS dummy light sometimes come on while driving my 96 Acura TL?

The TCS and ABS lights are not "dummy lights"! They are warning lights that are telling you the ABS braking system and the traction control systems are not functioning due to a problem in the system. You need to have the ABS system scanned for codes. The problem you have is usually caused by a bad wheel speed sensor. Since you have a sensor at each wheel you need the car scanned to find out which one to replace.