we have two kinds of THC, they are ST- THCEX02 and ST-THCEX03, see the picture below. You can change the parameter M38 to make it under automatic mode. You can find the parameter under DIAG interface. The default value of M38 is 0, if you change the value to 1, it means the THC under automatic mode.
For THC ST-THCEX02, if you change the M38 to 1, the torch will go up to end.
For THC ST-THCEX03, you will see the THC shows A000, and the torch doesn’t go up and down, it will be stay.