Wiring on 1974 MT 34

[nodestination]

Hi all. Does any one have wiring diagram fir 1974 MT 34. Two of my gauges stopped working. The tmp gauge was working fine and now hung at 160. The oil was working fine and now shows only 20 at any rpm. Check the oil level - fine. My alt do not work . I have 2 ground wire that are not connected. My engine clock runs 24/7 for last 10 month - since I purchase this boat. Some other wiring issue. Try search but no luck. Thanks

 

[bayview]

why not connect the ground wires and see what happens. You will be lucky to find a wiring diagram but those are usually straight forward items.


Hook up the wires, clean and tighten all connections. You know where both ends of the each of those wires are how they get there often doesn't matter. 12V is attached to each of the gauges probably from the same nearby source then the wires go to the senders, sender are often the ground but there may be a separate ground connection.


Senders for temp and pressure are usually just variable resistors to ground with the resistance dependent on temp or pressure. You can check senders with an ohm meter with the wires disconnected measure resistance. It will be between 100 hms and zero and should change with themp or engine running for pressure. Any $5 digital multimeter is good enough.

Multiple problems usually have a common fault, fix those grounds first.

 

[alormaria]

No wiring diagrams per Miller Yachts, the importer. The oil and temp are sensitive and balanced for upper and lower helm. The upper and lower must be connected and working for the others to work. The senders are specific for one or two gauges.

Please connect all grounds please.

The engine hour meter runs because it is powered. It does not need the engine running to count hours. There must be something wrong with the key switch. It needs to be wired to cut power to the lower tach when turned to off.

 

[FF]

Folks that are pulling apart an electrical system to clean the contacts might want to consider the purchase of a box of copper star washers.

These will keep tension on eye terminals after many heating and cooling cycles from DC operation.

 

[nodestination]

I need to change the ignition switch and re-wire. I think, that I may mess up the upper gauges when I pulled out to refinish the wood frame. Will check this out. Thanks

 

[nodestination]

Well, finally I fixed the wiring. All gauges are working. I learned on "the road" a lot. Dual station gauges are different that single station. The problem was in upper station ignition switch. Thanks all for the help and suggestions.