The causes and solutions of faults in water temperature gauges of construction machinery

The common faults of the water temperature gauge are: when the ignition switch is turned on, the pointer of the water temperature gauge always points above 100℃ without moving, and the pointer does not move accordingly when the water temperature changes. When the ignition switch is turned on and the pointer of the water temperature gauge moves to 40℃, the engine temperature rises, but the pointer does not move.

The cause of the malfunction is: the power cord is open-circuited. The heating coil of the meter head is broken. The heating coil of the water temperature sensor is disconnected, the wiring screw is loose, the meter head wire is disconnected, there is an internal short circuit, and the water temperature sensor has failed. The water temperature gauge has failed, and there is a ground connection somewhere between the water temperature gauge and the sensor wire.

The troubleshooting method is to check the ammeter (the contacts of the circuit breaker must be closed). If the ammeter indicates 0, It indicates that a section of the common circuit from the battery to the ignition switch power supply terminal is open. If the ammeter shows a discharge of approximately 5A, it indicates that the common circuit is energized, but there is an open circuit in the section from the ignition switch II terminal to the water temperature gauge and sensor. You can test the fire by grounding the terminal post of the water temperature gauge.

Place the middle part of a screwdriver close to the ignition terminal of the water temperature gauge, and let the tip of the screwdriver touch the metal part of the machine. If no spark appears, it indicates that the connection between the ignition switch and the water temperature gauge is disconnected. If there is a spark during the grounding test, use a screwdriver to ground the terminal of the water temperature sensor. If the pointer of the water temperature gauge quickly rotates to the 40℃ position, it indicates that the water temperature sensor is damaged.

The troubleshooting method for the fault that the water temperature gauge pointer always points to 40℃ is to close the ignition switch, and the water temperature gauge pointer will quickly rotate from a position above 100℃ to 40℃. When the engine temperature rises and the pointer of the water temperature gauge still points to 40℃, it indicates that there is a fault in the circuit from the water temperature gauge to the water temperature sensor. The wiring of the water temperature sensor can be removed for an open-circuit test. If the pointer of the water temperature gauge returns to a position above 100℃, it indicates that the water temperature sensor is grounded internally.