If you are using a Real Time Engineering (RTE) voltage limiter, it uses a red LED to indicate normal operation when powered by blinking.
From the RTE limiter installation documentation (with corrected grammar):
"There is a small LED that will flash when the limiter is operating properly. You should be able to see the LED reflecting off the circuit board. If the LED is off all the time, it may mean that one of the gauges is shorted to ground."