1989 GMC s15 -- Brake light flashing on dash
 

I have 1989 GMC s15 which is similar to s10...

the brake light flashing 9 times than pause and again 9 times...

I know it is indication of something but not sure what...can someone advice?

I see no one has answered you on your '89 GMC. Maybe this will get an answer for both of us.
I have a 1989 Chevy Silverado and my brake light came on and stayed on after having my brakes completely done by a good mechanic. I carried it back to him and he unplugged the ABS wires from the unit on top. The light went off and he said at that time it might come back on because he didn't know what was causing it to come on. I drove it about 50 miles and it came back on. Since it wasn't hurting anything I just dismissed it and drove it anyway.
Now last Monday it started flashing. It would flash 4 times the pause and again 4 times....

Can someone give us some help with the reading of this code or tell us what to do about it.
Thanks In Advance,
Derl

Same problem
 

I have the exact same issue on my 88 chevy. 9 short flashes then one long. My heater also stopped working with no light to the electronic display. I just read a post saying removing the negative batter terminal will hopefully fix and reset the control panel problem but that it also was connected to resetting the ABS module. It's a shot in the dark but im hoping to knock out two birds with one stone ill let you knkw if i have any luck with the brake light.