Welcome to Just Answer,
Do you have headlights or brakelights?
Where was the vehicle hit?
The anti-theft will not kill power to the vehicle, it allows the vehicle to start for a couple of seconds and then kills it.
Check pin 16 on the data link connector for power, it is the bottom right pin. I would look closely at the TIPM (Totally Integrated Power Module) this is the computerized fuse box in the engine compartment. It is also the gateway that all of the other modules communicate through. It is on the drivers side of the engine compartment.
Let me know where the truck was hit and I can give you more places to check.
Let me dig through some wiring diagrams, I will get back with you.
What fuse are you looking at, give me the number so I can reference it to my diagrams.
Are you saying that at the fuse itself you have B+ and the ECM has only 10 volts?
Are you testing the ECM on the side of the block or the PCM on the passenger firewall?
Your scanner can't read anything because the 06 Cummins is using a CAN network and most after-market scanners and code readers are not CAN enabled. The fact that you have power at the DLC and the truck will start means the ECM and Wireless Control Module are working. I would check the power and grounds to the instrument cluster, it is in essence the body control module in Chrysler vehicles.
Are you getting any lights at all on the cluster or is it completely dead?
The ECM is not a likely cause of the problem you are having, but I never say impossible, cars and trucks like to do the impossible. The voltage drop could be a part of the problem as that fuse may power other items. The fact that it starts and runs however badly indicates the ECM is online. The instrument cluster controls all of the interior lighting, locks windows most anything with a switch in the passenger compartment goes through the cluster.
The most likely culprits are the TIPM or the cluster, the TIPM controls all power flow and also acts as a gateway for the networks to communicate on. It is the fuse box with a control module attached. Check all of the fuses if you have not already, not only visually but with a test light. Pop out the TIPM and check all of the connections and wires, I have seen one wire not locked in a connector run me in circles.
If you need diagrams or pin charts I can get them to you on this post.
Finding out why the cluster has no power should be the first step, please remember my only contact with the vehicle is through you so I may ask a lot of questions that may seem uneccesary. One more:
Is it blowing any white smoke when it is running?
Sorry it took awhile to get back with you, I have an 04 3500 Cummins I am putting a motor in and it has to be done by Mon. so I have been working late.
I am glad we saved you a trip to the dealer.