If they replaced the supermanifold then it was likely a cooling/heating problem with the batteries that created the error and put the truck in limp mode. If my understanding is correct, they share one heat pump for heating/cooling the cab, and the batteries, and if the batteries don't stay...
I didn't have any problems engaging. They did stay engaged longer than I thought they would but I was on sand and not asphalt. A few minutes of going back and forth and they disengaged for me. Having spent a long time off-roading in a variety of vehicles and having many vehicles stuck in 4 low I...