Electric Riddle/Brain Teaser-96 Plymouth Gr Voyageur

Hello,

I have an electrical puzzle, if you will, with my van (96 Gr Voy). It actually dates back to Mar/Apr of this year but today it reoccured for the first time since then. What happens is I notice the interior lighting (dashboard readouts) flicker while driving. I checked battery connections, think that they're ok, but tighten down negative terminal anyway. All iseems fine; no flickering. I go to get battery/alternator tested and guy tells me battery is good but that the diode has failed. I open car door and notice no lights at all, therefore no electric to start the car. I then open the door a time or two and hear clicking near me from the area of the door. I close it once or twice and that seems to correct the Car Repair Talk's forum.