Troubleshooting Boat Gauges: How to Check if a Gauge is Functional

A few simple tests can help determine if you're boat's gauges are working properly. Follow these easy steps to determine if you're gauges are providing accurate readings. When in doubt, contact your local dealer with more technical questions.

How to test Fuel Level, Oil Pressure, Oil Temperature & Water Temperature Boat Gauges

Turn on the key.

1. Remove the S (sender) wire from the S terminal. The gauge pointer must move to below
the furthest left mark.

2. Next, short the S terminal to the G terminal. The pointer must go to the far right of the last
mark.

If the pointer moves left and right when performing the two steps, the gauge is functional.
The fault may be in the sender wire or sender.

How to test a voltmeter

Turn on the key. G

Remove the voltmeter from the panel and connect directly to a known good battery. I to battery positive. G to battery negative.

Gauge should read approximately battery voltage. A multi-meter test meter can be installed to more accurately read battery voltage.

*Remember, no wire is connected to the S terminal... ever.

How to test Engine Trim gauges

Turn on the key.

Remove the S (sender) wire from the S terminal. The gauge pointer must move to
pointer position shown per engine type.

Next, short the S terminal to the G terminal. The pointer must move in the opposite direction as shown per engine type.

If the pointer moves left and right when performing the two steps, the gauge is 
functional. Look to the trim sender or the wire in between for the fault.