Tach wiring location, can someone lead the blind???

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

bump

Mike, if nobody jumps before I get home I'll send you the wiring diagram.

thx

Mike,
If you have a concealed box you should have a plug coming out of the box going to the tach. 3 wires, 2 off the ignition switch, purple and black, Grey is the lead from the VR via the wiring harness. Turn ignition to on and purple wire will have 12vdc on it with the probes set to VDC and hooked to purple and black. On back of tach will be 3 posts, gnd, ign, sndr. Purple goes to ign, black to gnd, grey to sndr. Check the igniton sw and look for any bad splices to the tach. If all of the gauges work when either the master power sw is applied or the ignition switch is turned on and the tach doesn't respond, and all voltage checked replace the tach.

hopefully these will help
http://im1.shutterfly.com/procserv/4...108AbtGzdizaOF
http://im1.shutterfly.com/procserv/4...108AbtGzdizaOF
http://im1.shutterfly.com/procserv/4...108AbtGzdizaOF
http://im1.shutterfly.com/procserv/4...108AbtGzdizaOF

i worked with it a little last night and now its working, but intermitting at times.

i tried to locate the wires on the engine, with no luck.

i found all the wires in the control box, and i think its going to be just loose or damaged wiring. ill just replace the connectors in the control box and see if that fixes things

thanks for the help
and i will keep you posted