Can a bad voltage regulator or rectifier bridge cause a wiring harness to burn up?

Some time ago, my uncle's 2002 Ford F-150 had very strange electrical anomalies occurring. Everything from the starter randomly engaging the engine even with the key off to the lights going crazy and the horn blaring intermittently. When he took it to the shop, they told him his wiring harness was burning up and it needed to be replaced. So he forked out the cash and they replaced it, however he is still having some residual electrical issues. Is it possible he has a bad voltage regulator or rectifier bridge that is wreaking havoc on the electrical system because that's all that comes to mind when craziness like that occurs.