Manual hubs are an add on by a prior owner. Take them off and clean them well. Lightly regrease them. Old grease gets dirty and sticky. It will cause enough drag to activate the sensor. There are great videos on YouTube about servicing aisin hubs. All hubs are basically the same design so regardless of who built yours, the videos will get you thru.

90 LWB - Not your average bear

"You are what you are, and you ain't what you ain't." - John Prine