hour gauge

[Regal2800]

hi guys, one of my hour gauges have never worked since i got the boat a few years ago. Can someone tell me where the wires from the gauge run to? Are they powered when the key is in the "ON" position or when the engine is actually running?

 

[Fanfare]

With Detroit Diesels the switch for the Hobbs hour meter comes off a pressure sensor on main engine's primary fuel filter. This switch turns off the battery charger and turns on the Hobbs meter. I have found this pressure switch is highly prone to break and leak fuel into the bilge which might be why yours is not connected. I now always carry two spares. The newest switches have three connections, the ground, and one each of "initially on" and another of "initially off," each of which changes when energized. I became quite confused by the one labeled "NO" before realizing I was looking at it upside down, and it really read "ON".

 

[Andy B]

Jim, you were right the first time , the three terminals should have been marked ,NO, NC,common.
NO stands for normally open,NC normally closed, Pressure opens the NC contact and closes the NO contact.

 

[tonytrakovich]

I think I remember seeing a fuse for the hour meter inside the DC switch panel in the engine room.

 

[Regal2800]

Ok cool I will check it out. What pressure switch is it so I can get more?

 

[Beckytek]

Oil pressure.

 

[Fanfare]

It is an oil pressure switch, but not the same kind that actually reads psi. These are more like the ones in your car that turn the idiot light on and off. Detroit Diesel dealer or SAMS Marine can give you the part number.

 

[Glory]

You could easily connect the the you meter to the key switch. It's not likely there's a signal to your battery charger any longer, but possible. And if your hour meters are in the ER, you can likely get a 12volt signal from the alternator harness. Even if you currently have self excited alternator(s) the excite wire is likely still there. The same circuit can supply the batters charger if needed.

JM