kohler gen system 150k

[reed179]

I'm hoping someone had the answer before I spend thousands on a new control board. I have a150k kohler generator that's been giving me temperature reading problems. The background to the problem begins: I was performing a coolant flush. The generator was ran for 2 hours with a cleaner, drained and ran a water flush. Once I began the second water flush the water temp gauge didn't work. I ohmed the wires, they are good. I changed the sending unit located in the thermostat housing, which sends its signal directly to the gauge. I've changed the gauge. The resistor on the back of the gauge checks good. The gauge is getting correct voltage when the generator is running. Voltage is going from the temp sending unit to both the low temp light and the gauge. The light works as when I didn't have the heater plugged in and the water was cold, the low temp light was on. I switched the leads on the sending unit, the one to the light and gauge. The light works from both portions of the sending unit. The gauge will not work.
So, new gauge, tried 2 new temp sending units, checked wires, checked voltage and ohms. I don't have schematics for the board but I'm almost convinced the a resistor in the board which one set of witts runs through had gone bad. Any suggestions?

 

[Barbqranch]

Have you tried the temperature sender hooked to the gauge, but not in the machine. ie, w/ a match. Is it possible there is an air pocket keeping it from working (I know nothing about this particular machine)?

 

[Sierrasparky]

Have you tried the temperature sender hooked to the gauge, but not in the machine. ie, w/ a match. Is it possible there is an air pocket keeping it from working (I know nothing about this particular machine)?

If all was working properly before the flush, I would look at a air-bleed issue.

 

[reed179]

We have all the air bleed from the cooling system. I know the power wires run into the control board. I'm not sure what resistors it goes through, or possibly a potentiometer to adjust the voltage for the gauge. I'm thinking the problem lies in the control board but I don't have schematics for it.

 

[Sierrasparky]

We have all the air bleed from the cooling system. I know the power wires run into the control board. I'm not sure what resistors it goes through, or possibly a potentiometer to adjust the voltage for the gauge. I'm thinking the problem lies in the control board but I don't have schematics for it.

Seems odd that the guage would fail as you are performing a flush. Something else has gone wrong.

 

[GoldDigger]

We have all the air bleed from the cooling system. I know the power wires run into the control board. I'm not sure what resistors it goes through, or possibly a potentiometer to adjust the voltage for the gauge. I'm thinking the problem lies in the control board but I don't have schematics for it.

You can try following the path of the wires from the terminal along the board with an ohmmeter. Also visually inspect for hairline cracks and bad solder joints.
It seems an unlikely coincidence that some part of the board involving the sensor failed while you were in the process of bleeding, but coincidences do happen.
Is the gauge reading the same with a the sensor connected as with it disconnected? That would support the idea of an open circuit somewhere.
If you disconnect the sensor and put a voltmeter on the sensor terminals of the board (or at the end of the wiring harness) do you read a voltage?