Toyota Repair: arc noise passenger side kick panel, side kick panel, battery terminal

Question
i have been from time to time for the last few years been hearing a arcing noise at or around the ecu on the passenger side of my 92 toyota truck 4x v-6 3.0.i took the ecu out this summer to check for moisture and no luck as well as checked all the wiring to be sure there were no cuts or loose connecters and all looked well.i blamed it on moisture but it did it again and its 20 degrees now so do ya have any input?heres whats going on,when and only when i start the truck i hear this arcing sound from the passenger side kick panel area.i then turn the ignition key to the off position and try to start the truck again and its not there so the truck starts.the lights and guages all are fine when this happens and i pull the codes out of the ecu and all is well.from time to time it will reset my alarm system as if it would do when say a loose battery terminal or starter contacts go bad.soooo do ya have any input on this?thanks in advance and i look forward to seein what ya have to say.  

Answer
I doubt it's the ECU. It'd got two seperate power supplys with their own seperate fuses. It's entire metal case is a grounding point.
Are you positive the ECU case itself is fastened tightly along with the harnesses on it?

Honestly, I'd probably be looking at things like a flasher, or relay instead of the ECU itself.