2003 150 txrb

[dave3cowboys]

I am having this same problem the four wire connector is not hooked up but when i do and turn the key on the alarm goes off can you tell me which wire goes to what have green/red, green/black, on one side and gray,pink, and black on the other everything works fine with the conntector unplugged but the tach has never worked since i bought the boat last year can you please help.
The black wire goes to nothing

[boats.net]

Wire colors change on different model years and harness's but generally the green/red is no oil indicator, green/black is full oil indicator, grey is overheat indicator, pink is trim and balck is ground.
It has a short either in harness or in tach.

[dave3cowboys]

Should the black wire be grounded because there is nothing hooked to it?

[dave3cowboys]

put new tach in, it gets power but no signal from motor and narrowed the buzzer down to the gray connected to the gray/black stripe wire plug it up the buzzer stays on any ideaS PLEASE.

[boats.net]

Sounds like have a short between grey wire and ground in engine harness or gauge harness, have an open in green wire on engine or in main 10 pin harness going to key switch.