When I turn on the head light switch - Both high beam lights don't work and no dash board lights either. If the headlight switch is off then the gear position lights do comeback but still no dashboard lights.
I have checked all the fuses both the driver seat side and the one son the engine - all fuses light up with the tester. Also checked both bulbs - they are OK too.
I am thinking about the few possibilities :
- Bad relay fuse
- Bad head light switch , itself.
- Bad dimmer switch
- Bad ground wires / connections
Anyone can provide some suggestions as to how to check/ test for these possible faults and then replace or fix it.
Would greatly appreciate it.

Thank you very much.