Georgios, have you checked for service codes if you do not have Cat ET here is the flash code list
the diagnostic plug is near the ECM under the floor on the right hand side
3. Place the Start/Stop Key Switch in the Run position with engine off. When the machine Start/Stop Key Switch is turned to the ON position, the machine will display the Transmission Configuration Code as part of normal operation. For example, when the Start/Stop Key of a 140H is turned to ON, a "41" code will be displayed on the EMS transmission indicator lamp (1). The lamp will flash four times in rapid succession followed with a one second pause followed by one additional flash.
4. To enter the Diagnostic Mode of the transmission ECM, uncouple the diagnostic plug (2). At this point the ECM automatically defaults to the Active Diagnostic Mode. In the Active Diagnostic Mode the ECM will flash out the first Active Fault in memory followed by a three second pause and then repeating the original fault. The original fault will continue to be repeated until the diagnostic plug (2) is reconnected.
5. To enter the Active Diagnostic Scroll Mode, jumper sockets 1 and 2 of the diagnostic receptacle of the diagnostic plug (2). The control will display all diagnostics that are presently active on the system. A three second pause separates the codes as they are displayed. Removing the jumper while the control is displaying a diagnostic code will cause the control to repeatedly display that code. Replacing the jumper resumes scrolling.
6. To enter the Logged Diagnostic Scroll Mode, jumper sockets 1 and 3 of the diagnostic receptacle. The ECM will now display any faults which have occurred which are not presently active. A Diagnostic Code of "12" indicates there are no Logged Faults present. Removing the jumper wire while the control is displaying a Diagnostic Code will cause the control to repeatedly display that code. Replacing the 1 to 3 jumper resumes scrolling.
7. This mode is used to clear Logged Diagnostics from memory. To erase a code, put the control in the Logged Diagnostic Scroll Mode until the desired code is displayed and then remove the jumper. The ECM will continue to display the desired code. Jumper receptacle socket 1 to 4. The transmission indicator lamp (1) will turn off indicating the code has been erased. The lamp will remain off until either the Logged Diagnostic Scroll Mode or the Active Diagnostic Scroll Mode is re-entered. The above process can be repeated until there are no codes stored in memory. An active diagnostic code cannot be erased from memory.