E 350 conversion van 1987

I have tried to get my van repaired by several.. My problem is the power door locks are trying to lock and unlock by themselves. It will run my batteries down too. I have looked at the switches in the door. Where is the acuator, or what ever it is that tells it what to do? Is it in the engine area? I hear clicking in the dashboard or engine, but can't push the locks while I am near the engine. Please help me find a diagram, or a manual on the 87 e 350 van. I love this van, and we go camping evey year. Please someone out there let me know something..PLEASE
Thanks, Linda