Brake light on 1983 dodge power ram 150?

I have a red brake light on i just had my rear brakes changed but the light is still on what makes that light go on? i cant seem to find anything around the drum or brake shoes wear would the sensor be or what would set it off how can i fix this?|||sensor is usually on the master cylinder and is telling you you have low fluid check that|||An %26#039;83 Ram PU isn%26#039;t going to have a low fluid level warning light. That%26#039;s just the normal brake warning light, which is triggered by a sensor in your proportioning valve (a little metal block that the 2 lines from the master go into, and then 3-4 lines come out to the wheels, just below the master). It shows that there is some sort of an imbalance in pressure between the 2 brake circuits. A lot of times it will be on after a brake job because the wheel cylinders got pushed back in to make room for the new shoes. It will usually go out after you press the brake pedal a few times. If not, it could be that the proportioning valve needs to be reset, or the wheel cylinders started leaking when they were pushed in. Normally, it will come on if you have a fluid leak, air in the lines, or a bad master cylinder plunger.