There are some theories that there are 2 wires in TU154 planes marked same colour, and they could have been mixed up. As the plane spent 10 yrs outdoor under snow rain what not, various parts were extracted out of it for other, acting planes, and that the same parts were installed in it again, borrowed from other planes. That's whenn the two wires could have been mixed up.
Cannibals at work.
Very dangerous & wasteful of manpower, but probably necessitated by an austere financial environment. The aircraft was just a wheeled parts bin. Parts available for the taking, no formal control. Then came more operational necessity and they needed a complete aircraft-with interesting results!
