I've got an ABS light that I've had the parts to fix for quite a while, just haven't gotten around to it. The problem is the same as I've fixed before.
The ABS "motor" in the front drivers side of the engine compartment is mounted to a solenoid body, the part many hoses go into. The computer trips these solenoids to release the brake pressure of particular wheels. There are eight solenoids.
The solenoids burn out or go bad. The computer reads the bad solenoid coil and trips the light. The ABS test will give you the module code, as opposed to a wheel sensor code or other fault.
You can also see that the ABS module needs a working brake switch signal (without which you can't shift an ATX out of park). Also Orange/Yellow ABS power is from 30A Anti-lock fuse, and the system needs a working ABS relay, which is a normal automotive relay in front of the air filter box.
The trick to diagnosing a blown solenoid coil is to disconnect the wiring harness connector in the engine compartment, and probe the pins corresponding to each coil inside the solenoid body with a multimeter to check the impedance. For example, to measure the "left-front-inlet" coil, measure between pin 7 and 17 (diagram and colors for 1993 SHO, but gen 2 likely all the same).
They will each read something like 6 ohms. When you find a coil that has no continuity, has gone open circuit, then it's time to hit the wrecking yard.
