Why has my chartplotter stopped working, and how can I troubleshoot it?
My chartplotter was working last weekend, but now it sometimes stays black and occasionally restarts when I start the engine. How do I check whether it is a power problem or a fault with the plotter itself?
Answer
A chartplotter that goes black or repeatedly restarts often has a power supply fault, such as low voltage, a blown fuse or a loose or corroded connection. Check power at the display while it tries to start, then investigate GPS reception, chart storage or network connections according to what still works.
Check the power supply
A plotter can show normal battery voltage with no load, yet fail when its screen and processor draw current. If it restarts when you crank the engine, suspect a voltage dip before blaming the software.
Isolate the circuit before removing fuses, cleaning terminals or disconnecting cables. Keep meter probes from bridging adjacent contacts.
- Check the controls. Confirm the battery isolator, electronics breaker and plotter switch are on. Try the power button with a bare finger; some touch-sensitive controls do not respond through gloves.
- Check every relevant fuse. There may be one at the distribution panel and another inline behind the display. Remove each fuse and test continuity; visual inspection can miss a break. Replace only with the specified type and rating. If it blows again, stop replacing it and investigate the fault.
- Inspect supply and negative connections. Look for loose crimps, green copper, overheated fuse holders and damaged cable. Check that the rear power plug is fully seated and its locking collar engaged.
- Measure voltage under load. Compare voltage at the battery terminals with voltage at the plotter's supply connector during startup, using the pin identification in its manual. On a nominal 12 V installation, a difference exceeding roughly 0.5 V warrants checking the cable, fuse holder and connections.
A rested, charged 12 V lead-acid battery typically reads about 12.6 to 12.8 V; lithium batteries behave differently. The permitted input range varies by model, so check the manual rather than assuming every display accepts 24 V.
Black or frozen screen
If buttons beep or the network still recognises the display, check brightness and night mode. Shade the screen and look closely. A faint image can indicate a backlight fault.
For a frozen screen, try the normal shutdown procedure first. If it will not respond, follow the model's forced shutdown procedure, then disconnect its supply for about 30 seconds before restarting. Investigate repeated freezing even if a restart temporarily clears it.
With power off, remove optional memory cards and disconnect external data connections, leaving the display's required power connection. Restart and reconnect accessories one at a time, switching off between changes. Some systems depend on a separate processor or chart master, so check the installation layout before interpreting the result.