this is on a 2006 model van chassis? ( most RV's are built on the previous model year van)
it could be related to this:
"...TSB 08-028-06 for first-generation Sprinters, Chrysler states that a burned out or incorrect type brake light bulb could result in unrelated DTCs in the ECM or ABS/ESP control module. Also, corrosion in the trailer tow connector, as well as on the taillight circuit board, may cause similar erroneous and/or unrelated DTCs.
it could the computer is falsely sensing a problem and trying to control a perceived skid or roll.
what happens with trailer lights disconnected?
"...When confronted with unexplained DTCs that affect various modules, a technician should perform some preliminary checks to diagnose the condition. Check all brake light bulbs and verify that they are of the correct type (P21/5W – 12V 21/5W). The brake and park light are part of the same bulb. An incorrect bulb may bridge these two circuits. Ensure that there are no broken filaments and that the sockets are free of any corrosion. Verify there are no bent connectors or conductors."