The e-locker is a relatively simple locker system. Yes the rear e-locker, at times, does take a little more time/distance to engage/disengage. If its not engaging the quickest and easiest first step is to chock the front tires, jack and support the rear of the rig...tires off the ground and transmission in neutral. Key-on just to engage electrical circuit but not starter...turn the locker switch to engage...rotate the rear wheels and check to see if both left and right wheels/axles are locked together or not (very obvious one way or the other). On some/all (can't remember) 100 model years the transfer case needs to be in low range...unless you've done the circuit mod to permit the rear axle to lock in high range.
If it works on the jack stands it will work in the field. I've found the e-locker to more consistently engage when going slow...just like the operator's manual states: <5mph. I can get it to lock above 5mph but its more inconsistent. Also it helps to turn left/right/left, etc., to alter the speeds of each rear axle half...for quicker (relative

) engagement and disengagement.
If the dash light remains blinking and the ABS light is not lit be sure to thoroughly check wiring, especially the wires and junctions near the rear suspension/axle along with the e-locker position sensor.