"S141" is read as "Splice number 141" ......

It appears to be a grounding circuit.

 

gregjg, I deleted the new thread you posted on this diagram and moved tbear's response here. Please don't start multiple threads on a common subject. It leads to confusion that can waste your time.

- Jack

 

Sorry about that JackandJanet.

Thanks! tbear853

 

Technically, that circuit is a "signal-only" grounding circuit that only carries the grounding for the various signals. This keeps the current that flows from high-current circuits separated. Usually signal ground and chassis ground are tied together at or in the PCM.

The wires to S141 are only red in the diagram. Under the hood, they're gray w/red stripe/