PANEL 0301386 - Caterpillar

Typical Electronic Heater Valve Control Circuit COMPONENT DESCRIPTION:
The 3E6234 Potentiometer (temperature selector) has a resistance of approximately 5000 ohms from one end to the other. The 3E6406 Board Control Assembly applies approximately 8 to 9 volts DC across the potentiometer, and measures the voltage of the center terminal to determine the position of the knob. Troubleshoot the potentiometer by disconnecting it from the circuit and measuring the resistance with a 6V7070 Digital Multimeter (or equivalent). The resistance of the center terminal should vary smoothly as the knob is turned and the total resistance should be about 5000 ohms.
The 3E6406 Board Control Assembly provides +12 volt or -12 volt power to the water valve motor when the position of the temperature selector is different than that of the water valve potentiometer.
The 3E3719 Water Valve Actuator Assembly consists of a motor and a feedback potentiometer. The motor is connected to the pink and blue wires. It can be checked by connecting those two wires to a 12 volt DC source. The motor should run in either direction depending on the polarity.
Do not apply 12 volts to the motor leads for more than a fraction of a second after the valve reaches the end of its travel, or motor damage will result. Do not apply more than 12 volts to the motor.The feedback potentiometer can be checked with a 6V7070 (or equivalent) Multimeter, in the same way as the temperature selector described above.