Diagnostic Aids
WARNING: This page is about a different car, the 1994 Cadillac Fleetwood. However, it is still accessible from the selected car via links, so may be relevant.
A faulty or misadjusted park/neutral switch may set a false Code 24. Use scan tester to check for proper signal in Drive while wiggling shifter. Code 24 may set if vehicle is power braked (brakes applied and throttle depressed) for more than 10 seconds.