Hello guys, new here!!

I am writing this post, because I have some issues I cannot find answers to!
I have an 06 volvo with a cummins isx1 15.0L on 1,017,600 miles on it. Yesterday I casually driving when the red triangle with the stop inside, and the park light ( P ) came on and started beeping!! When I stop and put it in N it goes away! I went to shop and they hooked up a computer to it, but could not fix it because they were too busy. The active codes that we got are:

1. Active | Insteumental Cluster | Rear Axle Temperature - Abnormaly High current or short circuit to ground. | PID 78 | 6 | 1

2. Active | Safety Restraint System | Driver Air Bag Ignition loop abnoemally low current or short-circuit | SID 1 | 5

And other codes that dont make a difference. Now this stop triangle comes on when I drive for about 5 10 miles... Also what confuses me is that I had to make a left turn to which the truck leans to the right and after that the light went away and came back on after 5 - 10 miles.... Everything looks good on the truck, nothing is leaking also checked to see if the temperature on the rear axles and connection rod and what not is ok and it is!! I have no idea what could be causing thins! Please give me some advice !

Thank you in advance

 

Do you have any suggestions for me, like where to start, how to do it? Sorry for being a complete idiot, but these things are not my strong suit... but I need to learn one way or another !
Thanks