I handle maintenance for a youth center with four Express 3500's. On one, the traction control is engaging even in dry conditions causing a drop in engine power and potentially hazardous conditions accelerating in city traffic. Our mechanic is looking, with no success yet, to repeat the problem. He gets the light flashing and noise indicating it's engaged, but no power drop. Of course the weather the last week has been lousy so he can't duplicate the dry driving conditions yet. Any ideas?