ABS warning light

1991 Buick Park Avenue ABS: If the ABS warning light comes on at least once each time it is driven, accompanied by a quick fluctuation in the brake pedal pressure, and then goes off, or goes off upon restarting the car??? Is this possibly due to a defective wheel speed sensor rather than a defect or malfunction in the ABS control module itself?

That light is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code not just their translation into English and post it back here. It likely will have a format like P1234.

It depends on when the light comes on. It’s normal for this model to have the light come on and stay on at starting. This indicates that the ABS accumulator is pumping up. It’s gotta get into the thousands of PSI so it takes some time. Normally it’s supposed to take about 30 seconds, then the light will go out. If it’s taking longer, the accumulator motor could be getting weaker. If the light comes on at other times, you may be right about the wheel sensor problem, or it could be something else. You’ll need to have the ABS codes pulled to find out.