As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
COCKPIT FILLED WITH SMOKE DURING A LOCAL TRAINING FLIGHT. STUDENT AND THE INSTRUCTOR SHUTDOWN EVERYTHING AND LANDED WITHOUT INCIDENT. INSPECTION FOUND THAT THE TAXI CIRCUIT BREAKER HAD NO RESISTANCE IN ITS OPERATION, AND NO AUDIO CLICK. OPERATIONAL CHECK OF THE TAXI LIGHT ON THE GROUND STILL FUNCTIONED PROPERLY. INSTALLED A NEW CIRCUIT BREAKER OPS CHECK WAS GOOD.