I have 89 s10 and the brake light is illuminated on the instrument cluster. This truck has no abs. I have checked the brake fluid and it is at the proper level. The truck has a hard pedal. I was maybe thinking it was a brake fluid level sensor or the brake pressure sensor on the proportioning valve under the master cylinder. I don't have access to any diagnostic information so any advice will be appreciated.

I have 89 s10 and the brake light is illuminated on the instrument cluster. This truck has no abs. I have checked the brake fluid and it is at the proper level. The truck has a hard pedal. I was maybe thinking it was a brake fluid level sensor or the brake pressure sensor on the proportioning valve under the master cylinder. I don't have access to any diagnostic information so any advice will be appreciated.
Does it still have a full pedal and no fluid leaks?
Red brake light?
Unplug the sensors and see if it goes out.
Also unplug the emg brake switch.

Are you real sure you do not have rear wheel ABS brakes?
If brake light still on after sensor and switch disconnect.
Check for ABS codes by grounding H and A pins on diagnostic connector.
Post back any code you get.

i would go with the e-brake pedel, it works with a ground wire , when you set the e-brake it is ungrounded causing the light to come on