ICQ>

Wax is used in the PVC mix. It is both a process lubricant and extender. Too much wax is probably the problem with the decaying wire harness wires. As the wax is depleted either by chemical or heat attack the PVC components of the insulation crumble.

At the connector ends of the harnesses there is no stress relief for the wires so you have the above, coupled with the weight of the wire hanging from the connectors. Now add in vibration.

This also explains why the very same wires are usually in almost new condition on the other side of the firewall.

Phil