seems like they're always 0.
is that normal?
No, for a headlight the number needs to be 1 or 2.
Left headlight [headlight_l] = 1
Right headlight [headlight_r] = 2
Left taillight [taillight_l] = 3
Right taillight [taillight_r] = 4
Front left indicator [indicator_lf] = 5
Front right indicator [indicator_rf] = 6
Rear left indicator [indicator_lr] = 7
Rear right indicator [indicator_rr] = 8
Left Brakelight [brakelight_l] = 9
Right Brakelight [brakelight_r] = 10
Center Brakelight [brakelight_m] = 11
Left Reverse light [reversinglight_l] = 12
Right Reverse light [reversinglight_r] = 13