After some research I discovered that the unit has a built in battery source but takes its signal from the impulse of one of the spark plug wires. When I zip-tied the lead wire to the spark plug wire it started to function again, and has worked perfectly since.
Mine froze, but it froze with HH8.7, not the number of hours (around 150). So, I don't think mine just lost it's signal. But, I will try to check the wires leading to it again.