4X4 service light on

2008 jeep commander limited 4x4. Bought used about 6 months ago. Within a week, took it back to dealer for shifting hard. They found nothing. Took it to a Jeep dealer, they found broken differential mount as soon as the mech lifted it. Since then have had intermittent grinding going into reverse. Takes a few time of putting in neutral and or turning car off and on for it to go into reverse. Soon after that happens, next day or so, 4x4 service message is on and does not go into 4low. Have had codes ran. Dealer finds none. Neighbor who is mechanic finds codes using model specific, not a global scan. (Indentifix) Active code is c1438, stored codes are c1406, 1405and c140f. Transfer case bad vs actuator module and would this cause the grinding on reverse, if trying to go into neutral or 4low on its own due to module malfuntion? Tires are fine, no mismatch, however, we did have the low pressure warning after driving through ice/slush, which cleared after undercarriage dried. (Can I say I hate all this electronic stuff!) Any advice will help. I don't want to buy a 1500$ part of a 350$ module will fix it!