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If the liquid level is too low, the main oil pressure is too low. The reverse brake belt has poor servo, such as poor piston seal, improper assembly, leakage, etc. (only for reverse gear). Advance brake belt is defective, such as poor piston seal and improper assembly. Leakage, etc. (only for the forward gear) control the valve body assembly in the reverse gear! ) The service assist valve is stuck or damaged (only for the reverse gear). The control valve body assembly is forwardly blocked. The service servo valve is stuck or damaged (only for the forward gear). The torque converter clutch TCC pressure relief ball valve assembly is relieved. The ball valve is not in place, causing the torque converter to return to the input clutch assembly. If the input clutch housing seal 628 is damaged or rolled up, the sealing surface of the input clutch housing is damaged, and the input clutch housing one-way ball valve is blocked or damaged. If the clutch piston seal is damaged or the shift lever is located at Pf, when the vehicle is stationary or running at a slow speed, the accelerator pedal is deeply stepped on. Although the engine speed increases greatly but the speed of the vehicle increases little or not at all, the possible failure causes are: Oil pressure is too low or no oil pressure (such as oil pump shaft break) manual linkage misalignment drive chain break low speed brake with servo damage leakage forward stop brake belt servo is bad, such as brake belt burnout slip, servo piston Poor sealing, servo internal spring damage and other valve body failures, such as the 3rd one-way ball valve lost torque converter internal fault, no power output or insufficient power input clutch failure, can not Transmission power, such as damage or loss of the clutch housing seal, damage or loss of the input clutch housing one-way ball valve, damage to the input clutch piston, input clutch plate wear and slip, etc. Input one-way clutch slipping planetary gear mechanism damage S only no reverse gear or Reverse gear slip (normal forward gear) reverse brake belt servo failure, such as poor piston seal, buffer spring or spring seat loss or damage, reverse brake belt wear or burned reverse brake drum damage, or The input clutch case and the front row of the keyway of the reverse brake drum are damaged. The shift timing is incorrect. We know that the shifting time of each gear in the automatic transmission is not fixed. It is the speed of the accelerator pedal. That is, the rate of change of the throttle opening degree is related. When the driver slams on the accelerator pedal, the shifting time is delayed compared to the slow pedaling; the shifting time is also related to the vehicle speed. When the load is large (the same throttle as the slope or the occupant) â–¡ Under the switch, the speed of the vehicle will be lower than that of the small load, and the shifting time will be delayed compared to the slow pedaling. The shifting moment mentioned here is not normal, and the speed is beyond the range of the calibration value. Next, there is an upshift or a downshift. To judge whether it is advanced or delayed, refer to the shifting time curve or according to the feeling of the special tester. For the 4TC5E automatic transmission, if there is an incorrect fault at the shifting time, it may be The reasons are: power system control module P \ hardware failure or software correction information is incorrect. For the latter case, the reader may feel strange, the general company fault diagnosis instrument TECH2 is very powerful, can update or rewrite the control program in the PCM if Improper updates (such as writing control programs for vehicles of different models or different configurations may result in some inexplicable automatic transmission "faults".
Throttle position sensor OPS): Throttle position sensor misalignment or failure Buick car throttle â–¡ Position sensor voltage value does not exceed 0i65V at idle speed, then POVIA is the throttle â–¡ opening is 0%, if the sensor manufacturing error or installation error When the opening degree exceeds 0.7% at idle speed, the PQVI thinks that the TPS has a certain opening degree, which directly affects the shift point. If the throttle position sensor is damaged and the contact is poor, it will cause the vehicle to move frequently and irregularly during driving.
7. Transmission lockup clutch (TOC) fault TCC faults include poor combination, inability to combine and inseparable, combined and separated speeds are too fast, too slow, and the combination is not stable. The joint failure is in the 3rd or 4th TCC. Regardless of how the PCM adjusts the PWM of the TQC, the engine speed and the transmission input shaft speed difference are still too large (the normal maximum value is about 20~50r/nin), indicating that the TQC is not reliably combined; when in the I 2 block or in the step After the brake pedal, the TCC is still not separated (the engine speed and the input shaft speed of the transmission are not different), then the TCC cannot be separated. Possible fault locations are: TCC solenoid valve electrical fault or spool stuck torque converter clutch control valve or torque converter Clutch regulator valve stuck or stuck in the valve body and gasket is improperly installed or the parts are incorrect. The torque converter clutch pressure relief ball valve or spring is damaged or the seal on the turbine shaft is not properly driven. The turbine shaft bushing of the seat is worn or damaged. The failure of the torque converter assembly may be caused by the damage of different components. In order to facilitate the reader to judge the fault, the following parts are listed as different indexes.
Two-way rotation of the one-way clutch of the guide roller in the torque converter: the acceleration is poor at low speed and the two-way can not rotate: the acceleration performance is high at high speed. The input clutch C3 input clutch does not work: there is no forward gear and the third gear C2 cannot be separated: Only 3 gears can not be combined: no 3 gears and 2 clutches C1 can not be combined: the transmission can only be separated in 1 gear: causing 2 stops or no 2-1 downshift servo (brake band B2 and servo Assembly) does not work: causing no reverse gear input one-way clutch F2 does not work: no forward gear or reverse gear 3 gear one-way clutch F1 does not work: 3 gear or no engine brake low speed gear in manual 1st gear Does not work for clutch F3: no forward gear in â–¡ and manual 3rd gear; forward gear does not work in manual 2 and manual 1st gear: no forward gear in â–¡ and manual 3rd gear; in manual 2 and manual 1st gear There is no forward gear: no engine brake in manual 1 and manual 2nd gear. 04 brake B1 does not work: no 4 gears. (9) Maintenance example 1. The vehicle starts to turn; the vehicle speed is 60~80kn/h. ,Engine speed
Connect to GM's special fault diagnosis tool TECH2, measure the power system, the fault code is "P0730 - incorrect gear ratio", measure the shift time of each gear as follows: PCM according to input shaft speed sensor (ISS) and output shaft speed sensor The data of (CSS, ie vehicle speed sensor VSS) calculates the actual gear ratio. For each selected gear, the PCM compares the measured gear ratio with the stored gear ratio stored, if not within the specified range, Excessive slippage in the transmission causes the wrong gear ratio, thus memory fault code P0730. The condition for setting fault code P0730 is to detect the following gear ratio for more than 7s: gear ratio greater than 297:1 gear ratio at 243: 1~287:1 gear ratio is 1*62:1~233:1 gear ratio is 1*05:1~L52:1 gear ratio is 075:1~0i95:1 2-3 block is detected according to TECH2 The upshift time is 0 and the meaning of the fault code, it can be judged that the 3rd clutch is slipping. Disassemble the transmission, check the 3rd clutch disc and the friction plate, and it has burned. In order to eliminate the root cause of the fault, the control components related to the 3rd gear should also be dismantled. Remove the 2-3 accumulator and check it carefully. It turns out that there is a crack on the accumulator housing. The crack position is as shown in 1. It turned out that the car had been dragged to the bottom and replaced the transmission oil sump at the field repair shop. At that time, no other parts were removed. The 2-3 accumulator is installed at the bottom of the transmission. When the transmission oil sump is towed, the deformation is against the 2-3 accumulator cover. Although the outer surface of the cover is not damaged, the housing is damaged. Down to check, due to the blockage of the cover, the crack on the shell is invisible, causing unresolved troubles.
Example 2: Shifting shocks, especially at low speeds, occasionally feel the vehicle squatting forward and shifting too long. "Under normal conditions, the shift time of the automatic transmission is about 0i25s. If the PCM detects that the shift time exceeds 0i65s, it will increase the line pressure to reduce the d' shift time and adjust the adjustment. Until the limit can not shorten this time, the counter is increased by one. If the counter value is two during one stroke, the PCM will memorize the fault code P1811. According to the repair experience, the cause of the 4T65E automatic transmission shift shock often occurs in the electric Control element, this is two shift valve and one oil pressure control solenoid valve. If the shift valve and the oil pressure control solenoid valve are bad and the action is stuck, the shifting adaptation will exceed the normal range, and the fault code P1811 will be remembered. The shifting shock will be felt. It should be pointed out that the faults of the shifting valve and the pressure valve are often sporadic, so we often do not have the current fault code when testing with TECH2. P1811 will appear in the historical fault code. Trouble shooting after shift valve and pressure control solenoid valve.
Example 3, D block acceleration is weak, like doing a stall test; Nf is driving at the time; no R, 1, 2, according to the owner, the car suddenly heard a serious abnormal sound in the front when driving at high speed, then like stepping on Decelerate like a brake. After parking, check the appearance of the vehicle without oil leakage and other abnormalities. After starting the vehicle again, the above faults occurred.
Use TECH2 to detect the power system fault code as DTCP1811, measure the relevant operating parameters when idling, and find that the input shaft speed is 0 at P or Nf. Normally, at idle speed, the input shaft speed is close to the engine speed in P/N gear; The input shaft speed is 0 when the vehicle is stationary after the gear is engaged. The measurement result indicates that the transmission input shaft is braked (either stuck or a gear combination in the P/N gear).
Disassemble and dismantle the transmission, and found two abnormalities: First, the planetary gear mechanism is stuck and cannot be separated and rotated; the second is that the 4th brake wear piece is burnt.
After replacing the damaged parts, test the vehicle and troubleshoot.
Analysis of the cause of the failure, we believe that at the time the vehicle was driving in the fourth gear, the planetary gear mechanism issued an abnormal sound after the card was issued. The planetary gear mechanism is then killed, the transmission ratio is 1:1, which is equivalent to hanging the third gear, so the fourth gear is still combined, the transmission can not hang two gears at the same time, so it burns the 4-speed brake pad . After the planetary gear mechanism is killed, P or Nf is equivalent to 3 gears, and the vehicle will go forward; when Df starts, it is equivalent to hang 1st and 3rd gears at the same time. When accelerating, it will be like a stall test.
According to the owner, the car can easily be opened to 160kn/h, but now it can only accelerate to about 135kn/h. The power system was measured with TECH2, the fault code was 'P0370 incorrect gear ratio', the 3rd gear up 4th time was 0, and the tester felt that the vehicle did not rise to 4th gear.
Disassemble the transmission, check the 4th gear related parts, and find that the keyway at the end of the 4-speed shaft has been polished, as shown in 2. The car has traveled more than 100,000 dry meters. According to the repair experience, the transmission needs to be fully inspected and overhauled as appropriate. After replacing the 4-speed shaft and overhaul kit, the test drive is troubleshooting.
4T65E automatic transmission 4 When the keyway at the end of the shaft is very small, the vehicle with a long driving distance, especially on the CL8 car with heavy body, the end key groove of this shaft is seriously worn and even polished, resulting in no four gears. It is recommended that the repair shop should check the keyway of the 4-speed shaft end when disassembling the 4T65E automatic transmission with long mileage. If the wear is serious (some like a blade), it should be replaced in time.
When the vehicle travels to about 120 kn/h, the vehicle body feels vibrating. When the TECH2 road test vehicle is connected, it is found that when the torque converter lock-up clutch TCC is combined, when the PWM is increased, the vehicle starts to vibrate. This indicates that the TCC is poorly coupled, because the torque converter cannot be disassembled and repaired, and the fault is eliminated after replacing the torque converter.
Example 6: No matter where the gear is hung, the vehicle can't drive. According to the owner, the car has a 'beep' sound before the car, and it will be repaired in the future, which will result in the failure of the gear to stop the car. The vehicle is driving, the engine speed suddenly rises, the transmission.
Connect the oil pressure gauge to measure the transmission oil pressure. Disassemble the transmission and check that the oil recording shaft is broken, resulting in no oil pressure. When the oil pump was dismantled, it was found that the blades and the sliding sleeve were severely worn, and a deep groove appeared. After the oil spring and the pump shaft, the fault is eliminated. After checking the car repair file, driving more than 100,000 dry meters, there has not been An = oil. ATF oil deterioration, poor lubrication is the cause of this failure. Example 7. When the shift lever is in the P/N gear, there is a “click†sound inside the transmission. The other gears are normally dismantled and found that the bearing of the drive sprocket bearing is black. Bad, more troubleshooting.
At P or hour, the turbine and the turbine shaft drive the driving sprocket to rotate, and the driving sprocket drives the driven sprocket. The transmission input clutch and the planetary tooth structure are idling; after the gear is stopped, when the vehicle is stationary, the turbine is no longer rotating, and the pump Slip between wheels. Therefore, after the drive sprocket bearing is damaged, an abnormal noise will occur when P/峨, and the abnormal noise will disappear when it is stationary after the gear is placed.
Example 8: The fault light is on, the shock is blocked, the acceleration is shivering, and the brake is braked. Sometimes the flameout system is stuck and "DTCP1811" is connected. As mentioned above, P1811S-after the fault code, it will not cause the fault light to be on. Root experience The fault code P1811 is often accompanied by a shift shock, not the acceleration 4 or the brake when the brake is turned off. The P0742 is in the 2SL (V model is the fault code, so the fault code should be checked in the TFP manual valve position JT In Guanzhong, there is a torque converter clutch release switch, and the PCMg senses whether the TOC is working according to the TFP signal. When the TOC is commanded to be turned off (CFF>, if the PCIVfg detects that the TC3C sliding speed is -20 ~±25r/nin, then the fault is set. After setting the fault code code DHCP0742, the rave lights up the function indicator ML, and commands the TCC to be turned on at the maximum power, and the power system module freezes the shift adaptation value. When the fault occurs, the PVUV of the TCC is measured by TECH2 to reach 99%. When the braked vehicle approaches the stop, the TCC's PWM05 reaches 99%, causing the vehicle to even turn off when braking.
Analysis, the fault point can be divided into two parts: one is the TCC part of the solenoid valve, and the other is the TOC feedback component, such as the TFP switch. After the TOC solenoid valve and the TFP switch are replaced at the same time, the vehicle is tested and the fault is eliminated.
(To be continued) 2003 land cruiser electronic control components position Liu Xiaofei Chinese and English