[T2] Tailight wires, 74

[Squid]

Hi, I am next going into tailight wires on my '74 Westy, and I have tiied to follow color 'schems' on th 'manual', but just now have realized..that..if I 'ground' the test probe..to Baterry ground,, and then go to each 'function'..as in right TS or right BL, I should be able to attach a 'ground' to battery, and then 'get'  'hot' lead, and then figure out what is what?  Yes, I have colors..on wires, but, BENTLEY  does not match, so I put ground on Battery, ..'turn', item ..'on'..and then 'play with existing wires..to find tailight 'need'?
Cheers
Syd