Brake Light Trouble Code Meaning

Searched the forums and couldn't find this one.

My non-ABS 1990 Chevy K1500 brake warning light is continuously flashing a one long, nine short pattern. Googling around I saw something that on ABS systems, this means "open circuit to speed sensor" but since I don't have ABS I'm stumped. Anyone know what this means?

Thanks

Dan

I believe you are incorrect. Those models were equipped with rear wheel abs.
Look at you master cylinder, is there a black box attached to it? If so your truck is equipped and that is the module.

Well I'll be. I guess I do have ABS. I was reading in the forums of how these cars had an ABS light that went on in conjunction with the brake light. Since I've never seen that light I assumed I didn't have ABS.

Thanks!