Sorry Another S500 Wire Harness Question.

[Targa-NF]

Hey everyone. I know this subject has been beaten to death... And is a sore spot for a lot of us. Anyway I have just added a 1992 S500 to the fleet and she has a few issues with SLS and wire harness.
My question is with the harness. Is the wire problem mainly on the main engine harness "part# 140 540 1132 " or can it most likely the whole car wiring? And what about the rest of the " under hood " wiring?
Why I ask is because she is acting different then my C280 wire harness failure. The C280 just had running problems. But The S500 has no speedo, and when its raining every now and then all the gauge lights will flash and my seat belt light will start flashing like i just started car. The car runs very nice and smooth. No missing or any other sign of harness failure. Plan to dig into harness and have a good look at all wires when it stops raining. Its been Pouring for passed few days .
I know I should check out all wires before asking questions. But just wanted to hear what other people have found and any tips they might have.
Thanks. Jay