[Tiara Open] Tachometer red light always on- need help

[53kemper]

Wonder if someone can help me with this. I have a 1997 3100 Open with twin crusaders.  When I get the boat going the red light on left turns on and stays on. Some have told me its my bilge light but I dont think that's correct. Others have said one motor is not running at the same rpm's as the other meaning they are not synced. I have them both at the same rpm's while driving but the light stays on. Anyone ever had this issue and know how to fix it?  Thanks