560 SEC idle control unit

[Sondrusen]

I am having problems with either my idle control unit, or the wiring. However I am going full EFI on the car, as the old system is trash anyway, it was probably good when new. But I am sure not going to keep a car with a system that is closing 40+ years. So I won't waste any money on the original system. My question is though, have anyone had problems with their wiring harness? Did it need replacing or was it something that caused it be like that?