Garmin GPS/Sounder won't stay on when engine is running?
#1
Senior Member
Thread Starter

My Garmin 74cv turns on and functions fine when the engine is not running. As soon as I crank the engine the unit shuts off. When I try to power it back on while engine is running the until displays the normal "powering on" display and them immediately shuts back off.
Seems like an obvious power source issue but can't figure out why it won't power on when motor is running. The digital engine data display is showing the alternator is turning out juice.
Any ideas?
Seems like an obvious power source issue but can't figure out why it won't power on when motor is running. The digital engine data display is showing the alternator is turning out juice.
Any ideas?
#2
Admirals Club




Things that come to mind are:
Bad connection in the electrical.
Bad Alternator circuit on the engine
Bad Battery
Bad Garmin
How many engines, how many batteries?
New Setup or has this been working?
If you have a volt meter, you can start by measuring the DC voltage at the battery when Engine is off and when engine is running.
If you can, Compare to voltage at the Garmin as well.
Bad connection in the electrical.
Bad Alternator circuit on the engine
Bad Battery
Bad Garmin
How many engines, how many batteries?
New Setup or has this been working?
If you have a volt meter, you can start by measuring the DC voltage at the battery when Engine is off and when engine is running.
If you can, Compare to voltage at the Garmin as well.
#3
Senior Member
Thread Starter

single 300 Suzuki.....2 batteries . The unit had been working fine, but I did notice that the day before it stopped working when the engine was running that the unit would shut off anytime I trimmed the motor up or down. Thinking maybe it’s a bad battery.
Things that come to mind are:
Bad connection in the electrical.
Bad Alternator circuit on the engine
Bad Battery
Bad Garmin
How many engines, how many batteries?
New Setup or has this been working?
If you have a volt meter, you can start by measuring the DC voltage at the battery when Engine is off and when engine is running.
If you can, Compare to voltage at the Garmin as well.
Bad connection in the electrical.
Bad Alternator circuit on the engine
Bad Battery
Bad Garmin
How many engines, how many batteries?
New Setup or has this been working?
If you have a volt meter, you can start by measuring the DC voltage at the battery when Engine is off and when engine is running.
If you can, Compare to voltage at the Garmin as well.
#7
Admirals Club 


I had the same problem with my Garmin. The problem was the battery voltage dropping to around 9 volts when starting. This caused the unit to shut off automatically. Your battery or battery cables in the first place to look.
#8
Senior Member
Thread Starter

Tracked the problem down to a bad 30amp breaker wired inline between a battery and the battery switch. Breaker looked ok , not tripped, but when I bypassed it everything worked like it should.