New to boating just bought a 1972 glasspar cutlas with a mercury 115 thunderbolt was wanting to hook gauges back up has a sears tach in dash was wanting to know if and how to hook back up. Thanks
I got nothing.....Is there any other electronic components under the meter movement between the back shell? I can just see a cap.........Seeing the electronic components and their layout relative to the meter movement c/would tell me the wiring scheme.
Wondering however and if no other components, some of the old types used a "transmitter". Which was nothing more than a separate piece that wired in series with the gauge that DID contain the electronic components.
How many connections on the tach? Older Mercury ones (like ones that originally came with your motor) had 2 connections. One was ground and the other the brown wire sender. You would need to look at the motor's switchbox to make sure the brown wire is connected to it.
Newer tachs have 3 connections. Power, ground and sender. In this case the brown wire would be connected to one of the yellow stator wires on the motor's rectifier.
You need to see where your brown (sender) wire is connected in the motor.
Assume then, the yellow wire that is jumping the two terminal screws must be used to config the tach to match the engine's pulses/rev depending on which screw/s.
Seems simple enough, brown to switch box(?), black to ground.
