1998 Plymouth Voyager “Service Engine Soon” light came on… Using the
“On-off-on-off-on” ignition key trick yielded codes #35 and #42.

Code 35 Radiator Fan Relay
I had the Radiator Fan Relay replaced last year, on the basis of a
diagnosis (by a dealer) that the "service engine soon" code required
it. There has never been an overheating issue. Any idea what could
cause this?

Code 42 Automatic Shut Down Relay
No issues with starting or engine shutting down.
Could it be wiring or connection issues? How is the ASD relay
removed? It won't budge when I pull on it.