RPM gauge not hooked up

[Mch5jdm]

I recently bought a 2005 Smoker Craft with a 50hp Mercury outboard. Runs great. However the rpm gauge is not connected. I see several wire harnesses in the back (3 look like the same connector) but I’m not sure which one it is. Any thoughts?

 

[Chris1956]

A modern tach needs +12VDC, ground and a signal wire. Look for a cluster of purple, black and grey wires. Purple is +12VDC, black is ground and grey is signal.

 

[Mch5jdm]

Hi. Thanks for the reply. So I went out an looked for it and found a cluster of wires with a purple, grey, brown, and black. The harness has 4 connectors. One was going to the fuel gauge and the other 3 were not hooked up. The end of the connector of all three would fit my rpm gauge. Here is a picture.
My question is which one should I use or do the all do the same?
Also, why would it be disconnected?

 

[flashback]

keeps the hours down if your tach has a hour meter.

 

[Mch5jdm]

keeps the hours down if your tach has a hour meter.

Thanks. No hours meter on it. Just rpm’s.

 

[Mch5jdm]

So I hooked up one of the connectors. Took it for a spin. Nothing. I’ll try the other two soon. Any ideas?

 

[Chris1956]

The brown wire is likely for an overheat alarm.

Make sure you have +12VD on the purple wire, ign on, and -12VDC on the black wire. A voltmeter or test light can confirm.

Check the grey wire at the motor. it should be connected to one of the yellow stator wires, that come from under the flywheel, and travel to the voltage regulator.

 

[Mch5jdm]

Checked the voltage and sending wires all good. So I drilled a small hole on the side used a coat hanger to move the needle. It was really stiff but about after a few min of working it around it was nice and loose. Hooked it back up abd it works. Sticky needle.
Thanks for the help.