Glad its fixed.
Future reference thought you might be interested. DCT Reads out on digital odometer screen in our trucks. DCT= Diagnostic Trouble Code
Sounds to me like it was intermittent issue. Unless its running bad when code reader used it may not store that code long enough to read it. You have "hard code" it stores until erased with a code reader, and "soft codes" will clear them selves if problem stops. Normally in so many start cycles like 3. Each manufacture does a little different programming specific to them. If you have an intermittent issue pull over and attempt to get code while its running badly if you can.
1998 and Newer Model Rams
Turn the ignition on while pushing the odometer clearing button simultaneously. Engine codes will read on models with digital odometers. This feature also tests all dash panels.