Symptom: a 2003 Volkswagen Passat B51.8T sedan, equipped with the German company ZF 01V (5HP-19FL) hand / self-automatic 5-speed automatic transmission, mileage of 120,000 km. Prior to the car's transmission has been repaired in other repair shop, this time to repair the fault is no reverse gear, forward block shock, no crawling and transmission internal abnormal sound.
    Troubleshooting: the maintenance staff in the car after the maintenance, but maintenance to a certain extent, it is difficult to continue. Maintenance personnel after receiving the car, the maintenance staff asked their maintenance through. Maintenance personnel is so stated: first connected to the fault diagnosis instrument on the transmission electronic control system was detected, only found a P0730 fault code. When checking the height of the transmission oil level, found at least 2L or so ATF, ATF re-test, the failure did not change the phenomenon. As the factory maintenance of the new automatic transmission failure experience is not very rich, so can only do a simple demolition. Remove the oil sump of the transmission, found ATF was black and pollution, but did not find too much wear particles, so remove the transmission hydraulic control valve body for decomposition and cleaning, in the cleaning process did not find the slide valve wear And stuck phenomenon. After the test, the results of the reverse gear is still no crawling process, only the fuel door to 2000r / min or so to drive, while the forward block cold car crawling and the hot car did not crawl, so there is no road test.
    In this case, we are involved in the maintenance of the vehicle failure. The road test, the basic phenomenon of failure and the failure of the repair plant coincides with the phenomenon. So we first connect the fault diagnosis instrument, check the transmission of the electronic control system, in its fault memory to read P0730 fault code, the meaning of the fault code for the transmission transmission ratio error. The transmission control unit calculates the gear ratio by receiving the input shaft speed sensor G182 and the output shaft speed sensor G195. This type of fault code is generally the problem of slipping the internal mechanical components of the control unit, the sensor, the line and the transmission. By reading the dynamic data of the transmission and observing the actual fault phenomena of the transmission, we have locked the fault point in mechanical and hydraulic aspects, so we decided to dismantle the transmission.
    After decomposing the transmission assembly, it was found that several sets of friction plates inside the transmission were burned. Which is responsible for the reverse gear of the active components of the group B clutch, responsible for 2,3,5 block brake components of the C group of brakes, responsible for 1-4 block (low block and direct block) of the active components of the A group of clutch and is responsible for 4,5 Of the active components of the E group clutch burner is more serious, the most serious burning is the B group clutch and A group of clutch. Through careful inspection, it can be determined that the reason for the burning of the clutch of group B is that the clutch friction plate wears too large, forcing the clutch piston to increase the movement stroke. When the clutch sets the working pressure, the piston moves beyond the limit, Function failure. And the main reason for non-crawling forward A group of clutch piston seal caused by a slight damage caused by pressure relief. As a result, it can be determined that the transmission electrical control system stores the P0730 fault code because the transmission slips.
    In accordance with the automatic transmission overhaul standards, we replaced all the sealing components, burned friction plate steel, while the torque converter has been refurbished, and thoroughly cleaned the hydraulic control part and cooling system. After reassembly, road test troubleshooting. But the test did not take long, the new problem has emerged: when the transmission temperature reaches 90 ℃ or more, in situ shift lever from the P, N position to D position, the transmission will be in the impact of the phenomenon, The impact of the operation is more serious, and when the transmission after the completion of the highest block, the car in the taxi when the speed of 50 ~ 60km / h will appear when the impact of the feeling, in fact, is 5 block down 4 block shock, but all upshift (1 -5 block) all normal and other downshift point without impact.
    After careful analysis, we believe that the impact of the D block and 5 block down 4 block shock should be caused by the same problem. Through the shift of the actuator worksheet shows that the shift lever from the P, N shift to the D-bit, the main active oil circuit is the A group of clutch oil, and the transmission from 5 to 4 block is nothing but again Start the A group of clutch oil, so the problem should be on the A group of clutch oil pressure.