I tried pulling the manual for your engine (SW8 series) from Lionel support but got document not found.
That's OK because I know for a fact your engine uses the same board set- LCP2 and thus the manual from my SD70MAC is valid as far as this error and cab blinks and motor drive.
https://www.lionelsupport.com/...d-NonPwd%20Units.pdf
Page 44
Locomotive diagnostics
Our locomotive includes built-in diagnostics to monitor the condition of the main drive motor. If a problem is detected, the locomotive's cab light will blink a diagnostic code. If you see the light inside the cab flashing, press RESET (for LEGACY operation), 0 (for TMCC operation), or DIRECTION/power interruption (for conventional operation to attempt to clear the problem. The locomotive will immediately check itself again. If the problem persists, the cab light will blink the code again.
Number of Blinks Diagnostic Code Description
1 Main drive motor stalled.
Here was a similar topic with a recent engine where this safety feaure was discussed https://ogrforum.ogaugerr.com/...7#163461606138314857
Note the end result was the user had less than 18V on the track and thus invoked the low track voltage problem causing motor stall detection to kick in.
Again, in the manual on page 6 of TMCC operation, this key step.
Increase track power voltage to full power (no more than 19 volts AC). If a circuit breaker trips when you turn on the Lionel power supply, check the wheels of your locomotive to make sure they are all securely on the track. Check to make sure the track is free of all metals that may cause a short circuit.
Sadly it doesn't warn you of the consequences of what less than full voltage can invoke - stalled motor detection, especially when the motor cannot reach the commanded speed at the current track voltage.
