I have VMSpc and think it would meet your need at half the price. Assuming that you have access to a laptop, VMSpc plugs into the diagnostic port on your chassis and captures all of the fault codes, providing some short English information about them. In your engine shutdown case, it should at least give you a starting point. It probably does not have any more advanced troubleshoot aides that the more expensive tool suggested by Norm does.
We run VMSpc on every trip because, in addition to capturing the error codes, it provides more monitoring capability than the dash instrumentation, a least on our RV. We also run Street Atlas GPS program on the other part of the screen. The combination of the costs of the two packages to run on our existing laptop was just a little more than many pay for a GPS alone.
It works for me. BTW, here
(VMSpc) is the link to VMSpc but there are other places that you can buy it. "Buy it" is for the cables to do the actual connection to your chassis. You can download and play with the software itself for free.