Recently purchased used 1995 S-10 pickup. The front differential is not engaging, watched some YouTube videos and could not find answer to my problem. Any help troubleshooting would be greatly appreciated. Have checked some items to eliminate some obvious mechanical problems: Transfer case does not seem to be the problem, the front driveshaft is turning but wheels don't (had on lift and engaged). Found vacuum actuator and mounting bracket were defective and replaced both. Fuse in fuse box is good. Have current coming out of computer to differential (I believe through testing) but I don't appear to have current at wiring connection at differential where the cable from the actuator goes into the differential. I believe I have an electrical/electronic problem but am lost as to how to proceed. Is there a relay somewhere that I have no idea where it is located? Where the cable from the actuator enters the differential, does this control the engagement or is it related to the hi/lo function? When I searched for troubleshooting advice online, I'm asked about engine codes and vin numbers and have vin but I haven't found anywhere to plug a reader into the system. Again, this is a 1995 S-10 pickup with the 4.3 engine. Equipped with the "on the fly" dash push button (that I don't trust to engage "on the fly"). Previously had an older S-10 Blazer that had the floor shift engagement that I never had any problems with, and I wish I had the same system on this one.