2002 Dodge Dakota Lights Flash

On my truck (JUST bought in Jan. '09) I have this peculiar issue. With truck tuned on, NOT running, just about every light (headlamps, parking lamps, fog lamps, dash lights, interior light) blink like I am a Police cruiser. If vehicle key is turned off, no blinking. If I run the high beams, is seems as though the high beams don't blink, but you can still notice blinking as if the low beams are still on. If the light are turned off and the truck is on, the dash lights operate with no issues. The first time I noticed this was about 1 week after I got the truck. The blinking started VERY slow (once every 2 - 3 minutes) and as the lights warmed up, the blinking quickened. Now, I turn on the lights and they start blinking quickly as soon as they are on. I have changed the headlamp bulbs, the fog lamp bulbs, both relays and the main light switch. I have asked the dealership, auto parts stores and trusted mechanics for ideas about what could be happening. The first thing said is usually suggesting a wiring problem (an exposed wire grounding out). The problem is, it happens even if I am sitting still or driving. And I can be on a smooth or rough road and the blinking doesn't change. Then, I went to the dealership again and spoke to a service manager who checked it out. Between he and I, we think it might be improper wiring on an after market radio system. All that is left now is the radio component (it had wires for amplifiers and external speakers which I removed after discovering some wires were still exposed). The discussion was, if the previous truck owner installed the radio himself/herself, he/she might have "cut some corners" in the installation.

Dose this sound like a viable answer? Or can you think of another possible solution?

Have you ever heard of this before?

Thanks in advance of any assistance.

Ted Tiedeman