Multifunction tach hour meter not working

[outragesteve]

I have repowered with new F90 w/ multifunction tach.(New harness to engine, new tach) Previous engine was also an F90, 2005. The RPM's and trim indicators work fine. The hour meter is still on "0" although I have about 2 hours on the engine! How/where does the hour meter get it's reading? From the ECU or is is based on run time when the tach is reading the engine RPM. Thanks

[boats.net]

The gauge has a internal clock, it uses the tach signal to record engine running time. It will show 0 until it runs for an hour then will change to 1. If the tach is working the hour meter should work.