dash flickers at a constant pace when driver door is open.

What is your question?

I've own a 95 land cruiser, When i open the driver door or any to get in the vehicle...all the lights within the dash starts to flicker and a control pace. When i stick the key in the ignition and start the vehicle, it all stop and goes to normal as if nutting happen. Is it a low-battery problem or a security system problem?