GT V1

Headlight issue:
GT V1 had typical headlight problems, if the headlight won't turn off or won't turn on, that means the circuit inside the headlight has been burnt off, get the headlight, if the headlight comes with 2 plugs, don't worry it is still compatible, one of them is for the horn, which was available to later models.

Error 30:
GT V1 had some error 30 issues, usually it's the controller, get the controller. If controller doesn't fix it, get the classic Controller+Display+Mainline combo.

Error 21:
Current malfunction, get the controller.