What is this??

[MRD]

It's mounted on the stern of our 36 marine trader. Two large black wires believed to be grounds going in and out. Any ideas what it is?

 

[Nick F]

There appear to be two other wires coming out of it (green and yellow).
It says Johnson Controls on it - they make heating (HVAC) controls for buildings.
Unscrew the two screws holding the cover on it and take a photo inside - then we might have a better chance of knowing what is.

Regards,
Nick

 

[MRD]

Thanks, Nick, It's pretty hard to get my big body back there it might come to that. On and off thru the years I've gotten serious about figuring out what it is but always hit dead ends. Even google seems to be clueless. The boat doesn't have marine air. Has a Freedom 1500 Inverter. Has an Onan 5 kw Smart generator.

 

[TowLou]

Some sort of relay? Trace the wires? Or ohm it out?

Maybe what it controls is switched on the ground. Not ground, negative. See if it clicks as someone throws switches.

 

[hmason]

JC also makes a high water alarm.

 

[Nick F]

Open the box !

 

[Alaskan Sea-Duction]

Open the box !

Yes open the box grasshopper. We all want to see.....