Break light code on dash. blinks ten times then one long blink, and repeat while idling.

Go to autozone and have them hook it up to their code reader

is it the code really? or just the BRAKE light? maybe you're diggin' too deep. sounds like a reservoir that is low, and comes up to 'light off' when fluid returns to reservoir. yes...it's your brake fluid, and probably low because your pads are worn. You have to think like a primate once in a while./

the gremlins under the hood are procrocreateing

No 7jimmy7, it's hydrodynamics, and a sensitive (save inaccurate) float brake juice activator-

I hate when they do that !

abs? eqipped? wheel speed sensor? dirt in the cogs spinning past wheel speed sensor?

http://www.ehow.com/how_6903764_read-codes-1990-gmc-pickup.html

open hood and there is a brake control module under master cylinder, has 2 connectors, disconnect both connector for 10 seconds and then reconnect, start vehicle and see if light goes out, if not let me knoe, also check and see if your rear brake light are working