When battery switched on, Tachometers go crazy

[SailorDave]

When I switch on the battery, the Tachometers go back and forth and the engine lights blink red. Ignition switches won’t turn on. Any ideas?

Radio, blower and nav lights all work, connect and ignition switches do not. All was fine until i installed second battery after being out of boat charging. Did i short something out? Checked fuses, all looked good but cant tell with the 3 large relays.

 

[jcb1977]

When I switch on the battery, the Tachometers go back and forth and the engine lights blink red. Ignition switches won’t turn on. Any ideas?

Radio, blower and nav lights all work, connect and ignition switches do not. All was fine until i installed second battery after being out of boat charging. Did i short something out? Checked fuses, all looked good but cant tell with the 3 large relays.

Unfortunately it sounds you fried the connext screen. They are very sensitive to voltage spikes.

 

[Beachbummer]

Since you were doing some electrical work... I would suggest ensuring all grounds are reconnected. Some electronic equipment use ground as a reference for zero... I doubt that's what's happening here but in the off chance it is... Confirm all grounds are back to the battery and no black wires were missed when reconnecting to battery.

A long shot but something to try.