My dad's Volvo XC90 2006 2.5t recently had some issues with the automatic transmission. We changed the transmission fluid and after that we started having some issues.
The rpms went up during the shift and not engaging the gear. Right after, the rpms go down and suddenly engages creating a hard pull. The transmission even got locked once in the 4th gear. The error code indicated problems with solenoid S1.
We did replace the solenoid S1, S3, S4, S5. After that, the problem continues and now it is giving the following codes:
- Lock-Up Function. Slips or Does Not Engage
- 0001. Shift Solenoid S1. Signal Too High
- 4A00. DTC Desconocido
- 014A DTC Desconocido

Any advice about what can be the problem and/or the solution please?.

Best regards,

Lucas