shift interlock
 

dealer said it was a shift interlock that is making my 97 blazer key not wanting to come out after they put a new ignition switch Is there a valve that i can change on my own dealer wants to change shifter and switch 600.00

$600USD? Wow. That's ridiculous. You have to figure out if that is the actual cause of the problem. Even if it were the shift interlock solenoid in the shifter (assuming floor shifter), getting a used shifter from a junkyard is FAR more cost effective.