Chevrolet Repair: What test equipment do I need?, 91 camaro rs, coolant temp

Question
91 camaro rs overheating.  "Holdup scooby" great line.  I dont have any except a voltmeter.  What should I have?

Answer

Simplified Fan Circuit Hey,

 A voltmeter is about all you are going to need.  If you have one I assume you know how to use it?

 I drew a quick diagram on how that system works with Windows Paint.  With the key off make sure the fan spins and themotor isn't seized.  Turn the vehicle on and warm it up. When it starts to overheat you should be reading 12v measured over the two wires that go to the fan.  If yes, replace motor, if no, continue.
 The next step does not need the vehicle running but the key should be in the run position.  Jump the coolant fan relay pins (switch side) with the relay unplugged. This will force 12v to the motor.  IF it doesnt run you need to check for voltage at the relay.  IF there is voltage at the relay you have an open wire between the relay and fan motor.  If no voltage at the relay you have a blown fuse link.  Still no fan?  The coolant temp sensor monitors coolant temperature and lets the ECM know when to close the fan relay.  If your ac works you can put it on and the fan should run.  If you AC is empty you will have to jump the low pressure switch on the compressor.

Wayne