Tach wiring 77 Johnson 115

[whitejamie99]

I have done a search of archives and found numerous tach wiring posts but I still cant get my tach working. I have the wire from the S terminal on Tach to the gray wire in the Control Box that goes back to the engine through the wiring harness. The other posts I read said to connect the I terminal to the Ignition. Not sure what this means but I'm assuming a 12V switched position on the key so that tach gets power when switch is turned on. Other two terminals are positive and ground and I'm assuming positive is for the light bulb and the ground is connected to a good ground. <br /><br />How do I trace/test the gray wire in the control box to tell if it is even hooked up in the engine. There is a wire hooked up in the terminal block (on powerhead Slot 7? next to red wire) in the slot marked Gray but its hard to tell if this is the same wire.<br /><br />Jamie

 

[MGuckin]

Re: Tach wiring 77 Johnson 115

Try here for troubleshooting tachs. It is a pdf file from Teleflex.<br /> Tachs

 

[whitejamie99]

Re: Tach wiring 77 Johnson 115

Thanks MG. Thats the same gauge. I'll find which terminal in the ignition switch to connect to. Probably should be 12V switched on so it would be easy to test. May not have had a good ground on prior setup.<br /><br />Jamie

 

[whitejamie99]

Re: Tach wiring 77 Johnson 115

The tach now zero's out when I turn on the switch. But it doesn't track any RPM's. The Teleflex guide says rectifier may be bad? How does that work?<br /><br />Jamie