Ongoing Issue with Transmission Code AT-124
 

I have a 1998 Volvo S70 and a few years ago I started getting the AT-124 code (mode selector switch signal too low). It's very intermittent, sometimes it will come back within a day, sometimes it will take a year or more to come back. Of course it starts acting up when it's time to smog. Two years ago the transmission faulted DURING the smog test :thumbs_up:

Things I've tried so far:
-Cleaned PNP/range switch
-Replaced PNP/range switch
-Adjusted PNP/range switch
-Replaced S/E/W drive mode switch
-Checked wiring and connections at these switches

Anyone know where to go from here?

Added:

-Take apart and clean connector as S/E/W switch
-Add second ground to this switch
-Ensured correct operation of S/E/W switch

Another clue:
-When I press and hold the "W" button for 25 seconds, the code I get is AT-121 Shift solenoid S1, short-circuit to ground. I should instead be getting the AT-124 code, I think.

Any thoughts?