I seem to have this strange, rare braking problem on my '93 Suburban that occurs on average about 1-2 times a month. When pressing down softly on the brakes (and travelling no more than 25 mph/40kph), the anti-lock system kicks in and for the next 5 seconds (which seems like an eternity), the brakes barely respond, if at all. The pedal vibrates and the vehicle continues travelling forward while the ABS buzzes away and, eventually, after a scary ride of about 50-70 ft., it finally stops. I have already had a number of close calls with this problem and I can't figure out why it's doing this. Usually, when it happens, I ride up onto the sidewalk or neighboring lane in order to avoid a fender-bender with the vehicle ahead of me. Please HELP!!

I recommend visiting a trusted repair shop QUICKLY! This is definitely not a good thing. I'm by no means a brake expert, but maybe an ABS sensor has gone bad? Please keep us posted.

Take care,
Jerry

Here's something I found on autobuyology.com
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General Motors is reported to be having problems with some of its Anti-locking Braking Systems (ABS) systems. The ones made by Varity-Kelsey-Hayes Company have been reported on national television (aired on the West Coast, November 11, 1996) to be seriously flawed in design, creating potentially hazardous driving situations for owners and others who share the road.

GM says that the problem is with drivers pumping the brakes instead of holding steady pressure on the brake pedal. However 7450 '91-96 GM Suburban, Jimmy, and other GM vehicle owners have filed complaints, some disputing GM's claims that the brakes are OK and the driver's are faulty. 2006 GM vehicle owners have blamed accidents on failure of the braking systems which they say failed to work or stop the vehicle. 600 injuries have been reported to have been caused by failure of GM ABS braking systems.

USA TODAY March 4, 1997
Yet another article:
GM has been hit with allegations of ABS defects on 3.6 million 1991-95 Chevrolet, GMC and Oldsmobile trucks. NHTSA has 15,566 complaints about those brakes, and reports of 3,545 accidents and 703 injuries linked to the trucks' ABS.

Update: I took the Suburban to an authorized GM service center and they told me it would cost $2000 to service the ABS. In addition, they said they couldn't guarantee that the problem would disappear, since they're "not sure why it's happening in the first place."

Why is GM handling this problem in the same way that Ford handled the Pinto?