[Richard L]

The 5v appears as soon as the system is switched on when the dash gauge is on. It stays at 5V at "all time" until there is a faulty detected after the system is triggered.

If you wish to switch over to a new map when there is water flow, it is better to use the "water flow signal" output on the yellow wire of the green harness.

This wire has the following signal level:

1. No flow at idle: 0.5V
2. Flowing: 0.5V to 4.5V
3. Sensor fault: >4.6V

This is by far the most secure failsafe for your Unichip interface especially if you can use 1 & 3 as early warning.