Connect the leads of a multi-meter, set on the 20 ohm scale, to the lugs on the switch. In the brakes-not-applied position you should show a "1" on the meter which means an open circuit, no juice flowing. Then move the lever to the "on" position and the gauge should show "0" if it's good. If it still shows a "1" the switch is bad.
Last edited by Tiny; 09/25/2013 3:38 PM.