Well when you let the car level in to the 1st floor BPP should be high and BP1, BP2, BP4, & BP8 should be low in IMS. If that’s not true you need to use a meter to see why. All but the newest Tac20s use LON for the BP inputs so you’ll trace the signals through the CWID, in on con 403 and out to the LN card on Con 706. If you see the inputs correctly at the LN card with a meter but not in IMS you’ll need to see if you have a LON problem. Can you see the inputs correctly in LON Explorer or not. Could be a connection through the CWID or a bad LN card. Newer TAC20s bypassed LON and ran the BP inputs straight back to the 188E. With intermittent BP errors on these older cars making this change helps a lot. Oh and if you do see the BP inputs correctly in IMS but still get this fault make sure your directional limits and NTS inputs are in the right state.