Did you or the tech verify the light was not on already before the test? We have had customers try that crap before so we make sure to note and tell them before we run the test on the dyno of any lights that are on before we start. Try shutting it off 3 times, sometimes that resets the computer to diagnose mode on some models, also try running the 25 MPH at a high rate of speed, sometimes that gets stubborn trac control lights to go off.
Another way could be a disconnected sensor (hard failure). Vehicle started check engine and other lights go on. Then it is plugged back in and turns itself off, but other lights remain. Still has to be cleared by a scanner to get trac and abs off. Try it on the next toyota you encounter of that year and model. Be sure you have already smogged it!!!
I notice the trac light flashes when I hook up my scanner to pre screen. But after turning it off and back on, it's off. But it stated on after the dyno run. I told the customer it will reset but it didn't.
Not sure if this is relevant but I have seen on some of the newer Toyotas, not sure what year it starts, the underhood label says if the vehicle is equipped with four wheel drive or Traction control it must be done on a four wheel dyno. The cars that I have smogged did have a button for traction control but I TSI'd them because of the underhood label. I am not going to risk damaging a drivetrain on the rollers and I followed the procedures stated by Toyota.
My friend have 1 about 2 months ago. Customer went to the dealership to get it turn off cost 1 hrs labor. Customer come back and asked to pay for the cost to turn off the trac and abs light. He said no and customer filed to BAR. BAR visited him and tries to collect the money for customer. He said no to BAR too and stated he only performed OIS and not knowing it will caused the problem. He still not giving the money back till now. From now on if I see 2003-2006 4 runner I will let the customer know in writing it might caused the TRAC and ABS light on when perform smog inspection.