Fault finding next step help please

Hi everyone
I’m still trying to fault find as to why my series 3 heater plug light isn’t working and I’m now a bit confused and at the limit of my (limited) expertise. So far I have proven the plugs are good, and I have a new bulb in the dash but I don’t have volts at the ballast resistor. I’ve loosened the ignition switch which seems to have 5 leads/terminals, 3 red and two white. I seem to have volts at all of them except two (A white and a red) but I’m not really sure what this means and where to go next. I feel I’m close to cracking this but really need help.
Any thoughts gratefully received

Have you a brown and red wire from ignition switch to ballast resistor or a loose one nearby that’s come off
Power to plugs is when key on last turn before cranking