Brake light on dash always on.

[cnj101]

I have a 91 1500 stepside 4x4 350cid. The brake light on the dash comes on every time I drive it. It seems to happen at around 30 mph but I do not understand this because it doesn't have abs. If I apply the parking brake the light gets brighter so I know it is not that switch. The fluid is full. Does anyone have any ideas?

[SpitAndDirt]

Bad ground behind dash. The electricity is finding a ground through the brake warning lamp causing it to glow. You seem to have a wiring problem if it comes on at around 30mph.

[cnj101]

I have been watching it more closely. It comes on at exactly 37mph. I read another post with the same problem at the same speed and someone said it was an ABS problem, but I do not have ABS. There is a black box mounted to the master cylnder, but there are no wheele sensors anywhere on the truck. On sunday I went through the entire truck and cleaned all body grounds. Oh and my cruise doesn't work now either.

[SpitAndDirt]

What about rear wheel ABS? Could be the Vehicle Speed Sensor mounted in the tail shaft of the transmission.

[cnj101]

Is that where it is? I looked at the wheels and saw no sensors. Wow don't I feel stupid. Thanks for the info I will check it out.