Ignition on wiring to module

Hi to All,
My question relates to distributor pickup,there are two wires from the pickup that go to the ignition module,they are high and low,how does one find which one is which,according to the drawings low to W high to G on the module.
There has been a fire in the engine bay at some stage and lots of wiring with no color codes,bit by bit I have been replacing them with the correct color codes from a wrecked car.
My car is a 1983 v12 he xjs,with lucas constant energy ignition ,hoping some Jag owner can help with this problem
thank you in advance regards.

                                           Kanga

Des Bownds