What do you do when you encounter electrical issues on the boat? If your depth sounder blanks out while entering a questionable harbor, or the chartplotter craps out, when heading out?

The first step in troubleshooting an electronics issue is something you should have done before the problem arises! Read the owner’s manual. Some basic understanding of how the system functions, and is installed before troubleshooting is extremely helpful in recognizing common problems. Most manuals will also have a basic troubleshooting section, which can help point you in the right direction.

When a piece of electronics gear fails to turn on, start by checking the power connection at the unit for looseness or corrosion. If your DC power panel has a volt meter installed, take a quick look to verify that it shows the correct voltage and that all required breakers are on.

For electronics that work intermittently or lose certain functions, check the remaining plugs or wire connections. These could also suffer from corrosion or may have vibrated loose over time. Problems are corrected often by disconnecting cable plugs and plugging them back in. The same is true for inline cable connections, which can loosen due to excessive movement or vibration if not secured or mounted properly. Trace the cable run as well, while looking for breaks or other damage.

If a piece of electronics powers up but shows nothing on the display, start simply.

Check the display brightness and contrast settings. These settings get adjusted on purpose (to preserve night vision for example) or by accident to the point where the display is no longer visible under different lighting conditions. Similar features also generate “operator-induced anomalies.” An example, If your radar fails to pick up targets, for example, verify you’re on the correct range setting and that the gain/sensitivity features are adjusted correctly.

No-power issues

When you’ve verified all connections are tight, yet the problem persists, it’s time to break out the multimeter. Every boat requires one, and basic units are less than $10.

Stay away from light pen-type voltage testers, however. They indicate there’s voltage, but not how much. A critical troubleshooting flaw as many electronics fail to operate if the voltage drops below a certain level.

Checking the power to a piece of gear requires you to turn the unit off. Disconnect the power plug or access the terminal strip where power is connected. Then verify that battery switches and breakers are in the on position.

Set the multimeter to the appropriate DC voltage test setting (typically 12 volts DC, but you’ll need to verify this). Many of the higher quality digital meters will auto scale to the correct voltage, eliminating this step.

Measure the voltage by connecting the meter’s negative probe to the equipment plug negative lead and positive probe to the positive lead. If you accidentally reverse the probes, a digital meter will simply display a negative reading. A voltage reading of “0” indicates no power is reaching the unit. Common causes include a tripped breaker, blown fuse, loose connection, or broken wire. When a fuse blows multiple times when replaced, consider it a symptom rather than the problem itself.

A low voltage reading indicates low battery voltage. It can indicate additional resistance in the line (for example, a corroded or faulty connection). Verify that the correct amount of power is leaving the breaker panel. Then work your way toward the equipment to identify the problem. If the voltage shown at the meter is incorrect, verify the voltage at the battery is correct and proceed from there.

Another factor to consider is how steady or consistent the voltage is during equipment operation. Some electronics draw more power during certain operations. This is often due to a weak battery or possibly a corroded connection. Monitor your DC panel volt meter, or use your volt meter, while keying the radio to see if the voltage drops. (Whenever working around wires or electricity — even 12-volt DC — be aware of the issues and dangers, and the possibility of AC current where you’re working. Avoid it if you’re not familiar with what you’re doing.)