b) Set a voltmeter to the 300 volts scale. Place test probes on terminals 1L and 3L (see diagram) of the high limit portion of the thermostat. The meter reading should be the input voltage of the heater (see rating plate of the water heater). If not correct voltage, check for loose connections and blown fuse or tripped circuit breaker. c) To verify that the high limit switch is closed, place test probes onto terminals 2L and 4L (see diagram).