Unfortunately, bundle uniformity on older aircraft with numerous wiring modifications and repairs becomes less organized for formal location of actual wire runs.
Out of the factory, bundles are identified by colored tie-wraps (red for pilot's systems, green for co-pilot systems...), if those particular color tie-wraps aren't available after a repair, white is used. Pretty soon, everything has white tie-wraps.
We locate wires in bundles by using a "fox and hound". We trace the tone which helps identify which bundle a particular wire is in. We have to cut tie-wraps and spread wires apart to find the exact one we're looking for.