GM-GMC: fault code, gmc suburban, rear brakes

Question
I have a 1990 GMC suburban with a 350. The brake light in the dash is flashing 10 times then pauses then again 10 time on and on. what does this mean?

Answer
kevan  you have an abs code  that truck  has what gm calls rabs system you may require the valve thats right under the master cylinder. that controls the fluid to the rear brakes.  you may have a kinda spongy pedal if it is defective.  the computer part of the system really doesnt brake very often. but i have changed many of those valves.
i would have to go back to my shop to read the manual for the exact def of the code, but im out for the weekend.