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One of my tachometers has stopped working. 1994 Vista with twin 5L Volvo (they are 5L Ford EFI). I need to know if anyone knows how to test it without the engine running. This tachometer only has three inputs, a positive, a ground and an input. My boat is in heated storage (Northern climate), I can access it, but I cannot start it. I've searched all the obvious sources and haven't found a method. TIA

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Current Boat: 1994 278 Four Winns Vista

I got this from a Google search.

Bench Testing the Tachometer (Gauge Only)
Disconnect & Power: Remove the tachometer and connect its ground terminal (G) to the negative battery terminal and the signal (S) terminal to the positive terminal of a 12V battery or charger.
Check Movement: Turn the power on; the needle should sweep to around 3500-4500 RPM if it's working.
Check Resistance (Optional): Use a multimeter's ohm setting to check the coil's resistance between the terminals; a reading of 140-180 ohms often indicates a healthy coil.

This won't test accuracy, but applying power to look for needle movement might be a start. You might also check the harness for power and ground.

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Surface Interval: A scuba diving term for that time between dives to relax and prepare for life's next great adventure.

Current boat: '02 FW 268 Vista
Previous boat: '95 FW 190 Horizon