TOD flashing - code 31

My TOD system is throwing a code 31.

My shop tells me the error reads: Clutch solenoid short or open.

Anyone have experience with this code? The vacuum valves have been tested and are working fine. 4LOW is fine. Just the 4High TOD is messing up.

They think the solenoids in the transfer case need service/replacement. Can they be accessed in a cost effective manner?

THANKS for all replies.

2000 Trooper