Hello. how to check battery glycol heater?

[Arek]

 

[vcor]

Doesn't look easy to test. The 2019 Model S uses a high voltage for resistive heating, but it is controlled by a low voltage PCM signal to regulate the temperature and has a status output line. Further details would require some monitoring on a working car. I don't think a resistive test will work. There is a Coolant Heater Temp Sensor, but it's unclear if is part of the assembly. It appears to be a temperature-sensitive resistor and could be ohmed out, but I doubt these go bad.

It might be different in other years, as you didn't state what year your car is.

 

[Arek]

TMS S85D 2015