1. The pointer of the oil pressure gauge does not move
The fault manifests as the oil pressure gauge pointer does not move when the ignition switch is turned on and the engine is started. The diagnosis method of this fault is as follows:
Turn on the ignition switch, 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 inside the sensor can be pressed with a flat-headed stick. If the hands of the watch do not move, the fault is sensor damage. If the hands move, the fault is in the oil circuit.
When the terminal of the oil pressure sensor is grounded, if the pointer of the oil pressure gauge does not move, the fault may be on the connecting wires of the oil pressure gauge and the oil pressure sensor. You can check whether the power connection of the oil pressure gauge has power. If there is no power, it means that the power connection is broken. If there is electricity in the power connection, check whether the signal line of the oil pressure gauge has electricity. If it has electricity, the fault is in the oil pressure gauge. If there is no electricity, the wire from the oil pressure gauge to the sensor is broken.
2. No voltage output of generator
This fault manifests as the generator has no voltage output when the ignition switch is turned on and the engine is started.
There are two main reasons for the failure: one is the failure of the generator, and the other is the failure of the voltage regulator. The fault diagnosis method is as follows:
(1) Generator fault diagnosis method
Check the generator tape Check whether the generator tape is good and the tension is proper. If the tape is worn, it should be replaced. If the tape has insufficient tension, it should be tightened as required.
The method of connecting the voltmeter and ammeter is as follows: stop the engine, remove the ground wire on the battery and the lead on the "B" terminal of the generator, and connect a DC ammeter with a range of 0-50A in series with the removed wire Between the "B" terminals, take another DC voltage meter with a range of 0 to 50V and connect it in parallel with the generator.
Check voltage and current Disconnect all electrical equipment switches on the construction machinery to reduce the load on the generator. Connect the ground wire of the battery and start the engine to make the generator run at a speed slightly higher than the full load. 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 main electrical equipment such as lighting, turn signal, heater and so on. Observe that the indicated value of the ammeter should be greater than 30A, and the indicated value of the voltmeter should 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) Regulator fault diagnosis method
To judge the quality of the transistor regulator, you can use the method of measuring the magnetic field current. The specific method is as follows: connect a DC ammeter with a range of 10A 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 position of the ammeter has not moved, it means that the high-power transistor (or composite tube) in the transistor regulator is open, or the voltage regulator and low-power transistor are short-circuited.
If the indication value of the ammeter is stable at low speed, when the rotation speed is 800 ～ 1000r / min, the indication value of the ammeter continuously increases with the increase of the rotation speed, it is a short circuit of a high-power triode (or composite tube), or a regulator tube, a small power The transistor is broken.
If the indicated value of the ammeter is relatively stable at low speed, when the speed is 800 ~ 1000r / min, the indicated value of the ammeter gradually decreases with the increase of the speed, indicating that the regulator is good.
