RT4 not saving time / date

[BULL1T]

The RT4 won't remember the date and time. Once the settings are saved and the motor is turned off, the data is lost (once the car and the RT4 starts again it shows a completely wrong date in 2000 and a wrong time).

Any advise

[GiveMeABreak]

Likely to be that the backup battery memory cell in the RT4 is at end of service life (these can only be charged so many times) and after 20 years, I think it's done exceedingly well.

If thinking of replacing it, you must first ensure your unit is in fact an RT4 and not an RT3, as they have a completely different type of battery and are not interchangeable. If you're not sure, pop your VIN up.