One thing that I've found so far on the GEN1 GSM (jlr gj32-7e453-ab) I have here is:

ID 0x370
byte 6 = LED backlight dimmer (00 = 0% / FF = 100%)
byte 7 = LED backlight on (00 = off / FF = on)

We can adjust the backlight brightness. I didn't figured out any thing more yet.

I just bought this selector jlr gj32-7e453-ab. When I power it up on the bench, with just the kvaser on its canbus, it starts streaming just one message on the ID 0x1F0
0- 20
1- 00
2- 00
3 and 4 its a cyclic message, looks like some kind of check sum
5- 00
6- 00
7- 40

I just looked at the github ...