Not so fast fellas....
What year motor? On 1996 and up Systems Check engines, the horn will NOT sound when any of the tan sensor wires are grounded, UNLESS the engine is running.
The lights on the tach will light up for the fault that you are testing, but the horn will not sound unless it is running.
Older than 1996, the advice is correct.
Sorry, i should have been more specific, its a 1982 60hp rude E60TLCNM, i would just like to know if my control box horn is functional.
Thank you gents for the info.
Cheers.