Check the listing for details. DC 12-50V 30A PWM 2-4 Wire Fan Temperature Control Module Voltage Speed Control. Color: Contact temperature measurement, Condition: New. Listed at 12.21 USD. Note: The 4-wire fan speed display and stall fault detection function can only be used on one channel. The 2-wire and 3-wire fans do not have speed display and stop detection functions. If the 4-wire fan is not connected for use, the speed switch must be turned to the OFF position, otherwise E3 alarm will appear and it will not work.