gauges replacement help needed

TomF-BHW

Cadet
Joined
Mar 24, 2019
Messages
10
Looking for help to understand how to switch out my speedometer and tachometer gauges on 2001 Boston Whaler Ventura with 200hp Mercury Optimax.
I bought new gauges but the plug on tachometer is different from the existing one. Not sure if they sell simple adaptor to make compatible or if new harness wiring needed etc.
here are pictures of old and new. The plug with the red part is the new one.
Thanks for any help.
 

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badrano

Petty Officer 1st Class
Joined
Aug 7, 2018
Messages
331
Looking at the pic of the merc harness, is it just the 3 wires? I see Purple, Grey, Tan. Purple is IGN power to the gauge, Grey is the tach signal and Tan is the temp sensor. Did the original tach display water temp?

Is the red part just a blank plug? Is it supposed to plug in to the new tach?

You might have to pull the connector off the harness and wire up a connector that plugs in to the new tach.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
The tach looks like is is some sort of multi function gauge. A standard tach needs only 3 wires, like the black harness.

Since the gauge is a Mercury part, see if you have a compatible plug already on your wiring harness. Om my '98 Johnson OB, the harness has the standard 3 wire plug for a tach, plus an 8 pin connector for the "System Check" tachometer.

System Check tach has RPM, overheat alarm, low oil alarm, no oil alarm and Check Engine alarm. Your tach may have something similar.

A search on the tach part number should shed some light.
 
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