I wish they did, but it is something you have to add. I've done it on my last two DP's so I have proportional input to the toad and it works great. I purchased the kit from https://m-gengineering.com/ I know there are a number of other systems that are equal in quality, but this is the one I first used and have stuck with them.

The concern it you have to isolate the coach from the toad in the event of a line brake to ensure you don't loose all air pressure. The kits have a separate air tank with valves to ensure the coach air does not bleed out in the event of a line breaking.