Possible causes and solutions:
1. Low transmission fluid (ATF) level
* Check the ATF level using the dipstick.
*Add fluid if necessary using the recommended type of ATF.
2. Contaminated or old transmission fluid
* Replace ATF and transmission filter according to maintenance intervals.
3. Problems with the torque converter (GDT)
* The diesel engine may slip or fail due to wear or malfunction.
*Consult a certified mechanic for diagnosis and repair.
4. Malfunction of solenoids
* Solenoids control the flow of transmission fluid in the transmission.
* Faulty solenoids can cause improper shifting and loss of power.
* Diagnose solenoids and replace faulty ones as necessary.
5. Worn clutches
* Worn clutches in the transmission may slip, resulting in loss of power.
* Worn clutches need to be replaced.
6. Sensor malfunction
* Faulty sensors, such as the transmission speed sensor or transmission pressure sensor, can provide inaccurate transmission performance data, leading to shifting problems.
* Test and replace faulty sensors.
7. Problems with electrical wiring
* Check the transmission wiring for damage or corrosion.
* Repair or replace faulty wires or connectors.
8. Transmission control module (TCM) malfunction
* The TCM controls the operation of the transmission.
*A faulty TCM can result in improper transmission control and other problems.
* Diagnose the TCM and replace it if necessary.
Note: Accurate diagnosis and repair should be left to a certified mechanic as transmission problems can be complex.