Fire switch control, the possibility of damage to the light switch can be eliminated. In addition, the ignition switch No. 2 pin has power when the key is in the gear position, and thus supplies power to the A alternator field coil transistor regulator C ignition system, the combined relay E instrument alarm lamp G stop light switch, and the like. Among the 7 power supply lines, the watt 2 road leads to the instrument board, and the luminaire is on the instrument board, and there is a high possibility that the two will have a short circuit fault. According to this, along the tile road to check the terminal on the instrument board, it is found that the insulating rubber pipe on the wire end is not placed on the root, and the fastening nut is slightly loose, the joint is deflected, the conductive piece is exposed; meanwhile, adjacent to the terminal The printed circuit connected to the lamp has a wear scar. Although the printed circuit board is coated with an insulating layer, it cannot withstand the friction and wear caused by the bumping vibration of the car, and finally is short-circuited with the conductive sheet.
Troubleshoot Loosen the fastening nut on the terminal block, set the insulation hose, tighten the nut after pulling the positive joint, and turn on the ignition switch. The lamp width lamp is no longer lit.
Fault Analysis The lamp width of the car is controlled by the light switch. The two are shorted to the same post. They should be lit when the light switch is pulled to the 1st gear. As long as the car is turned on, the lamp and the wide lamp are lit at the same time, indicating that the current is directly supplied to the lamp or the wide lamp via the ignition switch. Since the current of the vehicle is normally supplied to the instrument and the warning lamp via the ignition switch, and the lamp and the warning lamp are on the same plate, there is a possibility of a short circuit between them. Therefore, when there is a failure to turn on the ignition switch wide lamp and the lamp is lit, it is generally determined that the device is short-circuited, and the search can be surely found. The brake fluid is mixed to cause the brake to be delayed, the side is flat and the faulty vehicle, and the 045 series off-road vehicle. When the brake pedal is depressed during driving, the braking effect can be immediately generated, but the brake pedal cannot be released immediately. It is often difficult to get started because of the drag of the wheels.
The joystick can be fully returned, and the brake pedal free-wheel brake drum and the shoe clearance are all in compliance. Remove the brake drum check, the shoe return spring is intact and no damage, the parking brake cable also meets the requirements; but after the brake pedal is released, the brake cylinder piston does not return, and the replacement chestnut dish is replaced. The fault has not been ruled out. Finally, the fault was eliminated after the brake line was replaced, but the original fault reappeared after less than 1000 km. After asking the driver to know that the car had added brake fluid not long ago, he suspected that the brake fluid was in question.
Troubleshoot the brake fluid and thoroughly clean the brake system. After adding new brake fluid, test the vehicle and the fault is completely eliminated.
The fault analysis is based on the inspection and elimination process and result analysis of the vehicle fault, which is caused by poor brake fluid flow. This is because, in the case of poor brake fluid flow, when the brake pedal is depressed, the brake fluid can quickly flow to the brakes to release the brakes due to the large forced pressure; When the brake pedal is used, due to the limited tension of the return spring, the brake fluid cannot be quickly returned to the master pump by the sub-pump, and the brake cannot be quickly released, so that the brake is delayed. However, if the brake fluid does not flow smoothly, the brake fluid may be different from the original brake fluid, or the original brake fluid may be used for too long, resulting in impurities or deterioration of the brake fluid due to chemical reaction. As a result, the flow resistance is increased and the above failure occurs. Why does the car suddenly fail to automatically upshift when the car is driving normally? After Wang Gong enters the car for 500,000 kilometers, there is a sudden failure to automatically raise the gear during normal driving, that is, there is no high-speed gear.
Working normally, confirm that the fault is in the automatic transmission. Then the automatic transmission was removed, and the disassembly check found that the transmission oil was dirty and had become black. The car used the monthly magazine and there was a large amount of metal scrap in the oil; the direct clutch piston was seriously worn, and the first piston ring of the piston head no longer existed. One piston ring is detached and damaged.
The welding method is used to repair the piston to remove the teeth of the hydraulic pump before welding to prevent annealing; then the piston is placed in the incubator for heating, and the temperature is suitable, then the welding is carried out with 307 nickel-based welding rod, and the welding current is preferably 7090 amp; After welding for 4 hours, the workpiece is re-turned until the workpiece is cooled to normal temperature, so that the piston returns to the standard size. After replacing the piston ring and installing the re-testing vehicle, the original fault no longer appears, and after half a year of use, the effect is proved to be good.
Fault analysis Due to the severe wear of the piston head of the direct clutch, the first piston ring is damaged and falls off, resulting in failure to seal, and the necessary oil pressure cannot be formed, and the transmission cannot automatically upshift. The root cause is that the maintenance work of the car is not in place, which accelerates the wear of the above-mentioned parts. Why does the car's transmission fail, and the åŽ Yongjun malfunction phenomenon, the 1090 type truck, no matter which forward gear is running normally, the engine is running normally in the neutral position, but the reverse gear does not work, and When the reverse gear is engaged, there is an abnormal sound of the tower tower.
The fault check is based on the fault phenomenon and is estimated to be inside the transmission. Then the transmission was unloaded from the vehicle and disassembled and inspected, and it was found that the reverse gear was seriously worn and the reverse bearing was seriously damaged.
Trouble-shooting After replacing the reverse gear and bearing and installing the re-testing vehicle, the abnormal sound no longer appears and the reverse gear function is fully restored.
After the failure analysis, it is understood that the car mainly undertakes the short transportation task, so the reverse gear is often used, causing the reverse gear to be seriously worn and the reverse bearing is damaged. In this way, the reverse gear on the reverse gear 2 shaft of the transmission intermediate shaft and the reverse gear on the reverse shaft are too loose due to the meshing clearance, so that abnormal noise occurs during the reverse gear, and even the meshing is not performed. It doesn't work. Editor-in-Chief Sun Guowen
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