Clicks can be confusing since numerous other relays and circuits will be turning on and off. To find out exactly what's happening, use a test light to measure the voltage on the larger cable on the starter solenoid. You'll find 12 volts there. What happens when a helper tries to crank the engine? If that voltage disappears, there's a bad connection somewhere in that cable, typically at a mechanical connecting point like the battery or right there on the solenoid.
If that voltage stays solid during the attempted cranking, measure on the smaller terminal next to it. 12 volts should appear there only when the ignition switch is turned to "crank". If no voltage appears there, we have to go back to the starter relay to take some readings.
Wednesday, January 2nd, 2013 AT 2:08 AM