Truma Ultrastore water heater (gas)

[Tyrella]

Van has recently been serviced, but found that the gas control switch did not show green/red light. Checked the following and all ok:
Current flow from board to appliance.
PCB and fuse. Also tried new board.
Cable from appliance to switch.
New control switch.
Earth bond.
STILL NO LIGHTS on control knob?

 

[Damian]

If everything else is OK, as you indicate, then there is a problem with the control switch, or more precisely the light within.

 

[Tyrella]

If everything else is OK, as you indicate, then there is a problem with the control switch, or more precisely the light within.

Thank you for your suggestion. A new switch was also tried and still no lights?