i have a 140hp johnson
mod J140TLCRD 1984
1984 model crossflow.

my tach is intermitting and i have found that if i wiggle the kill switch, that it will work briefly, im wanting to replace the lead wire (which i have found out that it is grey) but i cant trace it to the motor, and i cant read the elect. specs in the manual

can someone tell me in lamens terms where to locate the grey wire on the motor end, and how and why it has anything to do with the kill switch.

can i bypass the control box all together, or is it neccessary.
trying to get some readings after rebuild, but without a tach im out in the dark.

thanks for any help