Antilock Brakes
 

87 951. The antilock lights up when turning on the ignition and on start-up it lights then goes out. In 4 yrs. of some very hard braking I've never had the light come on or feel the classic pulse in the pedal. Oddly the only time the dash light came on was when the car was running on stands while trying to duplicate clunking coming from the rear. Was not able to duplicate clunking BTW and have not heard/felt it since, but First time I touched the brake pedal antilock dash light came on and stayed on until I turned the engine off. On restart lights as usual then light goes out as usual. While continuing trying to duplicate clunking while running on stands applied brakes multiple times antilock dash light did not come on. Other than this one instance has the dash light come on in the last 4yrs. Is it possible my ABS is not working? Is there a way to test?

Any dirt/gravel roads around you?

Sounds like normal behavior (except for when on the stands and the light came on). Do you get the fart sound from the ABS pump when you start driving?
Find a cold morning and when the tires are still cold, get up to ~40 mph, then stomp on your brakes until you come to a full stop. The fronts should lock up and you'll feel the pedal pulsate. It's pretty evident in these older systems. Alternatively, as suggested, a gravel or dirt lot works as well.

IIRC, the dash light does not come on in normal operation. I've never noticed it anyway. I think if the light came on it's because the ABS computer detected a fault with the sensors. I'd check the sensors, make sure they're secure, check the wiring etc. With the car on stands, the suspension was extended more than normal - maybe there's a pinched wire on one of the sensors? If it happens again, it might be worth pulling the ABS computer connector and checking the contacts to see which sensor(s) are the problem. The pinout diagram should be out there. Let me know if you need it and can't find it - I have the factory ABS test plan booklet.

I find it very difficult to force the ABS to engage unless it's pretty slippery outside. Even with cold summer tires in the winter, I can't get it to kick in if the road is dry, and I know because I've been trying a lot lately, in order to troubleshoot something.