John,
If it is _just_ internal lights on the Jayco Pin2, then you could attach to the same pin 3/4 (12S) that you used for the fridge. That way it would be switched with the ignition. But one of your earlier posts suggested that the Jayco pin2 also powered the battery charger for the Jayco battery? IF that's the case, I doubt you'd have enough current draw capacity in the D4's wiring/plugs to drive it, and you'd end up overheating the wiring. In that instance, don't do it.
Cheers,
Gordon

