explained. >> reporter: he says electronics are the likely culprits, interference with the electronic systems. toyota says it's not true. they say -- inside the electronics lab at the university of maryland's clark school of engineering, professor mike peck specializes in laboratory-controlled interference testing. >> they need to be continuously be testing these products. you just can't test one day and say, ah, there's the problem. unless they can make sure there's no other changes, and that's very difficult today. >> reporter: and that, he says, may be the heart of toyota's problems. professor, i realize you're trying to be careful and maybe reluctant to say some things. but the floor mats don't seem to be the problem. a mechanical fix in the gas pedal doesn't seem to be the problem. in fact, the problem seems to be