rpm stopped working @SAME TIME AS OIL CHANGE LIGHT STOPPED WORKING

i HAVE A 90 SC! MY RPM GAUGE JUST STOPPED WORKING AT THE EXACT SAME TIME AS THE OIL CHANGE LIGHT BUT THE RAD OIL FUEL LOW LIGHT ALL STILL WORK BUT I UNPLUGGED THE BOX ANYWAY JUST IN CASE!ANYONE KNOW IF THESE R SUPPOSED TO B CONNECTED OR IS SOMETING TERRIBLE WRONG!:smokin:

You will have to get a wiring diagram for your car to see if these circuits are connected somewhere.Ask for a Mitchell electrical manual at your local library. You could ask your question at the Super Coupe forum at sccoa.com.