Repair and troubleshooting of AMT gearbox faults in heavy-duty HOWO A7 tractor
Vehicle information:
Vehicle model: HOWO-A7 6 x 2 tractor
engine: D10 340hp
Transmission: 16 speed overdrive AMT
Driving distance: 312435 kilometers
1、 Fault phenomenon: There have been multiple instances where the starting gear cannot be engaged, and other gears are also difficult to engage during driving, often jumping into neutral gear
2、 On site inspection, perform the following inspection steps:
1. Checked AMT and did not find any current fault codes
2. During the on-site test drive, it is indeed difficult to shift into the starting gear. Try 7-8 times, only 1-2 times can successfully hang in
3. While parked, use a diagnostic tool to measure data and diagnose faults, monitor transmission related data, and discover
The output shaft speed of the gearbox experiences violent and disorderly fluctuations, ranging from 20-2000 revolutions per minute. However, the output shaft speed 1 (odometer sensor) remained below 0
The position of the clutch is also changing. Getting off the car and watching the clutch rocker arm move forward and backward indicates that the clutch is constantly engaging and disengaging
4. Preliminary judgment shows that the fault lies in the output shaft sensor or clutch cylinder
Check the clutch cylinder core and no wear was found
When checking the output shaft sensor, it was found that the output shaft speed sensor was loose, and it was raining that day, which may cause water to enter the sensor
Reconnect the output shaft sensor plug, and after testing, it was found that the fault had been resolved
3、 Repair Summary:
The timing and gear selection of AMT shifting are mainly determined by the current posture of the vehicle, among which vehicle speed information is one of the very important factors
AMT vehicle speed information mainly collects: 1. ABS vehicle speed information; 2. Output shaft speed sensor information; 3. Odometer sensor information
When one or both of these three vehicle speed information are lost, AMT can still work; But if one of the speed information is chaotic, it will bring great trouble to the AMT's shifting timing and gear selection, often resulting in incorrect shifting timing and failure to select a reasonable gear according to the actual vehicle condition
This type of malfunction generally manifests as no problem shifting gears in place, but inability to shift gears or chaotic shifting while driving. The general processing procedure is to disconnect the information of these three speeds (odometer sensor, ABS, output shaft speed sensor) separately