The low range button flashes for about 5 seconds on my ML270 when engine starts and then goes off - is this normal?

Yes, it is normal for the low range button to flash for a few seconds when you start the engine on your ML270. This typically indicates that the vehicle's system is performing a self-check to ensure that the low range function is operating correctly. Once the system confirms everything is functioning properly, the light will turn off. If the light stays on or flashes continuously after that initial period, it may indicate a problem that needs further investigation.