Need Help with Satoh S-650G temperature light

bobpsr · Aug 28, 2013

Is the temperature light supposed to illuminate when the key is in the run position and the engine is off and cold?
The owners manual says "Set the starter switch to "ON" and confirm the oil pressure warning lamp, battery charge warning lamp and water temperature warning lamp.". It does not say what you are confirming. I assume all 3 of the lights should be on until the motor starts. It goes on to state specifically that the oil pressure warning light will be lit in the on position and will go off when running normally. The battery charge warning lamp section also states specifically that the lamp is on when the key is on and not running and goes out once the motor is running normally. The water temperature section only states that the light wil be lit when it gets too hot. It does not say that it will be on when the key is on but the motor is stopped and cold. I am getting ~11V to the wire going to the water temperature sender when it is disconnected from the sender on the intake manifold. I put the bottom half of the sender in boiling water while monitoring the resistance and it never reads anything but open circuit. The part number in the parts manual is 0180540, but I have been unable to find one (without purchasing an entire intake manifold assembly).
Does anyone have a substitute part number?

knothead541 · Aug 28, 2013

The light is off when the ignition is on unless an overheated condition exists. You may not be able to get the sensor to close with just boiling water since operating temperatures may often be above 212 deg. in a pressurized cooling system. You're probably ok with the sensor providing the wires, bulb and connectors are good.

Ilikeurtractor · Aug 28, 2013

You can test the switch by heating oil on your stove and using a candy thermometer (or equivalent) to watch the temperature. Vegetable oil is fine or motor oil in a metal container. The switch should operate in the low 200s F degrees. Don't heat the oil over 300 - if it doesn't close by then the switch is defective. You can test the temp light by jumpering the connection from the sensor connection to ground and see if it lights up. You should only need the key in the run position to do this test, engine can be off.