77:N is down NTS deceleration switch, according to the manual, this fault will auto recover as fateinc2005 indicates. this indicates you are missing the down nts signal while coming into the bottom floor. I have not worked on this equipment, but i would think it would log the fault and reset, then run in the up direction ok. but i guess if you run up and the down nts switch fails to come back on maybe that would cause you to fault again. it looks like the signal 77:n comes from the Car 61 bar reader, to the 806 lceccbn board, then to the lce 385 drv board, then to the 375 LCE cpu board. to test, compare the voltage on xc11-7 connector on the 375 LCE board which is the 77:U or up nts switch, and the xc11-8 connector on the 375 LCE board which is down switch, if car is in middle of hatch, both of these signals should read 0vdc with respect to ground, I believe, I could be wrong the switches may be open already in which case you would read 24vdc to ground. in any case they should be the same. if you run car down on inspect and pass the switch the voltage should change, compare up and down to check. if down switch is not changing then head to cartop and check switch in same manner.