on my 88 FC the rpm,s on the cluster would work some times but then would stop working, but now my rpm gauge doesn't even work anymore. What sensor reads my rpm's? and where is it located? Please help a brotha out!

 

The tach reads your RPMs... the signal is sent from a wire at the trailing coil. Y/B IIRC.

 

How can i check if it is working properly?

 

i think this may not go well, as youre calling your TACH an RPM gauge...

 

I meant to say that the wire was yellow and blue.

To see if it is working properly... start the car, and rev the engine duh.

You need a separate tach to hook directly to the coil to test, or some other method of verifying engine speed - but since you used the term "RPM gauge" you may want to ask for help with this.