The mileage is about 116 thousand km, carrying the FS5 A - EL 5 speed electronic controlled automatic transmission in 2006 FAW Pentium 2 sedan. The vehicle's fault indicator is often AT, the transmission has no manual control mode, and the instrument manual mode lamp "M" does not display, and it is obvious that the car's fuel consumption is increased. Fault diagnosis: first, connect the X431 diagnostic instrument for correlation detection. The faulty memory has an accidental fault code of P0744 (torque converter clutch control voltage is too high). After clearing the fault code to test the car, everything is normal, but after a period of time, the "AT" light is lighted again. At this time, the automatic mode shift of the D bit is normal but no manual control mode. The TCC solenoid valve data flow always shows 0, that is, no TCC locking control (fault mode), so that there is no mechanical connection between the engine and the automatic transmission. The process will result in heavy oil consumption and high speed transmission. Replace valve assembly (with solenoid valve) and special ATF. The failure phenomenon disappeared. The owner of the car was used for a few days before the "AT" lamp was lit again. It was found that ATF was especially black and stinks. After the replacement of the popular ATF, the problem is improved and is delivered to the owner again. A few days later, the owner reflected that neither the forward nor the reverse gear could drive. The car was towed to the repair shop to disassemble the gearbox. It was found that the forward clutch and 2, 4 and 5 brake belts were seriously damaged. Change the related parts according to the overhaul standard and test the car after loading. It is found that the cool car is basically normal, the 3 gear of the hot car is delayed and the shock feeling is accompanied by the 3 gear. Sometimes when the speedup test is run, the fault indicator light will light up, but the P0733 (3 gear ratio error) is reported, then the transmission will be locked in the 3 gear. Repeated test cars, this phenomenon can not be eliminated, considering the mechanical aspects of the less possible, and then replace the body again, but the result is still the same, at this time the maintenance is in a deadlock. Because the computer set the transmission ratio error fault code condition is the pressure of hydraulic pressure, mechanical components skidding and so on, suspected of control problems, after the replacement of TCM, the failure is still. Inspection found that the failure rule has always been related to temperature. Therefore, the special ATF needed for the transmission is replaced, and after the replacement of ATF, the fault is obviously improved. But the test is still a problem after a certain degree. The transmission is based on the original Mazda M64 gear automatic transmission gear structure based on a single row, and also a clutch, a brake and a one-way clutch to achieve the 5 first 1 inverted transmission functions, as shown in Figure 6-3. The automatic transmission is detailedly checked again. It is found that the 2, 4 and 5 gears are burnt again. Observe the power transmission process of the entire transmission. When the transmission operates from the 1 gear to the 2 gear, the oil passage is controlled from the working oil passage of the brake belt. In order to ensure the comfort of the gear shift, the pressure of the oil path is precisely adjusted, eventually making the brake belt fully engaged to complete the second transmission process; when the transmission performs 3 gear controls, the pressure of the working oil path is not cut off, and the same adjustment pressure is exerted through the release cavity of the brake belt. At the same time the pressure is equal at both ends, but the back spiral spring at the release cavity and the servo piston of the brake belt is released by the spring force to release the brake belt and stop working, and finally complete the 3 gear transfer process. When the transmission is carried out in the 4 gear control, the computer will be able to cut off the brake belt release chamber pressure and then the brake belt will be reacted again. The second step is to complete the 4 stage power transmission process. When the transmission performs 5 gear control, the brake belt continues to work like the 4 gear without any changes. The power transmission process and failure phenomena of several gears of the gearbox are integrated, indicating that the accumulation point of the problem is around the 2, 4 and 5 brake belts. Check the brake belt servo mechanism, found that the brake belt piston promotion and transmission shell contact parts wear. In order to further verify the wear degree of the piston sales and the shell of the brake belt, the piston is loaded into the transmission shell and measured by the dial meter. The result shows that the volume of the swinging is large. Troubleshooting: replacement of transmission housing and brake belt, troubleshooting.