1. The pointer of the oil pressure gauge does not move
The fault shows that when the ignition switch is turned on and the engine is started, the pointer of the oil pressure gauge does not act. The diagnosis method of this fault is as follows:
Turn on the ignition, start the engine and ground the oil pressure sensor terminal. If the pointer of the oil pressure gauge moves at this time, it indicates that the pressure gauge is intact, and the fault may be in the oil pressure sensor or oil circuit. The sensor can be removed and the diaphragm in the sensor can be pressed with a flat head stick. If the gauge needle does not move, the fault is that the sensor is damaged. If the needle moves, the fault is in the oil circuit.
When grounding the terminal of the oil pressure sensor, if the pointer of the oil pressure gauge does not move, the fault may be on the connecting wire of the oil pressure gauge and the oil pressure sensor. Check whether the power wiring of the oil pressure gauge has power. If the power wiring has no power, it indicates that the power wiring is open circuit. If the power wiring is energized, check whether the signal line of the oil pressure gauge is energized. If so, the fault is the oil pressure gauge. If there is no power, the wire from the oil pressure gauge to the sensor is open circuit.
2. The generator has no voltage output
The fault shows that when the ignition switch is turned on and the engine is started, the generator has no voltage output.
There are two main causes of the fault: one is the fault of the generator, and the other is the fault of the voltage regulator. The fault diagnosis method is as follows:
(1) Generator fault diagnosis method
Check whether the generator tape is in good condition and whether its tension is appropriate. If the tape is worn, replace it. If the tension of the tape is insufficient, it shall be tensioned as required.
The method of connecting voltmeter and ammeter is as follows: shut down the engine, remove the grounding wire on the battery and the wire on the "B" terminal of the generator, connect a DC ammeter with a range of 0 ~ 50A in series between the removed wire and the "B" terminal, and take another DC voltmeter with a range of 0 ~ 50V and connect it to the generator in parallel.
Check the voltage and current and disconnect the switches of all electrical equipment on the construction machinery to reduce the load of the generator. Connect the grounding wire of the battery, start the engine and make the generator run at a speed slightly higher than the full load speed. Observe that the indicated value of the ammeter should be less than 10a and the indicated value of the voltmeter should be within the rated voltage range of the regulator. Turn on the lighting, turn signal, warm air and other main electrical equipment on the equipment, and observe that the indicated value of ammeter shall be greater than 30a, and the indicated value of voltmeter shall be greater than the rated voltage. If the detected value does not meet the above standard value, it indicates that the generator is faulty.
(2) Fault diagnosis method of regulator
The method of measuring magnetic field current can be used to judge the quality of transistor regulator. The specific methods are as follows: connect a DC ammeter with a range of 10A in series between the regulator "F" and the generator "F" terminal, start the engine and let the generator generate electricity.
When the engine speed rises, if the pointer of the ammeter does not move, it indicates that the high-power triode (or composite tube) in the transistor regulator is open circuit, or the voltage stabilizing tube and low-power triode are short circuited.
If the indicating value of the ammeter is stable at low speed, and the indicating value of the ammeter increases with the increase of the speed when the speed is 800 ~ 1000r / min, it is a short circuit of the high-power triode (or composite tube), or an open circuit of the voltage stabilizing tube and low-power triode.
If the indication value of the ammeter increases gradually at a low speed of 1000r / min, it indicates that the indication value of the ammeter decreases gradually at a stable speed of 1000r / min.
