2002 mercury 40hp 4 stroke efi warning horn and no start

[Coop99]

I have a 2002 mercury 40hp 4 stroke efi. When the key is turned to on, there is no sound, not even the fuel pump priming. After about 20 seconds a continuous beep sounds, main power relay clicks on, and the fuel pump kicks on and runs non stop. I know the warning means low oil or overheat but I unplugged both sensors and the horn didn’t shut off. motor cranks but will not fire

 

[CCanada]

I have a very similar problem with my 2005 Mercury 25hp 4 stroke EFI. My engine won't start until I get the beep. I have to turn the key on several times before I get the beep. The fuel pump does not run until I get the beep, I have replaced the ignition switch which did not help. I have checked the wiring between the control box and the engine. It is good.
Have you found out what your trouble is/was yet?