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 local 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? We also had another one of them in the dealership for the same issue, but they could not find anything either. All have 50-70,000 miles. At least three have exhibited some similar symptoms to varying degrees.