Check abs system lite on how do you find the code list

ABS Fault Code List 1991 Corvette (C4)
Code Definition
21 Right Front Wheel Speed Sensor Fault
22 Right Front Toothed Wheel Frequency Error
25 Left Front Wheel Speed Sensor Fault
26 Left Front Toothed Wheel Frequency Error
31 Right Rear Wheel Speed Sensor Fault
32 Right Rear Toothed Wheel Frequency Error
35 Left Rear Wheel Speed Sensor Fault
36 Left Rear Toothed Wheel Frequency Error
41 Right Front Solenoid Valve Fault
45 Left Front Solenoid Valve Fault
55 Rear Wheels Solenoid Valve Fault
61 Pump Motor or Motor Relay Fault
63 Solenoid Valve Relay Fault
71 Electronic Brake Control Module Fault
72 Serial Data Line Fault
75 Lateral Accelerometer Fault (Short ot Open)
76 Lateral Accelerometer Fault (Signal out of Range)

Check each wheel in turn ,and where the sensor is their is a metal knurled ring ,make sure its not spinning around on the shaft