Chevy truck brake pedal pulse when stopped

[morepwr]

Maybe somebody can lead me in the right direction on what to look for or what is wrong with my truck. Its a 1991 chevy 1/2 ton 2wd. When I am stopped at a stoplight, the pedal pulses some.

I am assume this is caused by something on the ABS. This year truck has rear ABS only. The brakes work fine and the truck stops good and I ony notice the pulse when stopped. The brakes are in good condition, no leaks from any lines or wheel cylinder. The fluid is full and everywhere I inspect, I am not seeing any problems. I have seen the brake light come on in the dash but it only stays on a few seconds and then goes out and I might not see it again for several minutes.

Thanks for any ideas.

 

[mechtech2]

Try cleaning the sensor rings and sensors [magnets] at each wheel. Rust and dirt impeded how they work.
Even if it does not fix the problem, it HAS to be right to go on.

 

[Dakota1820]

Could be drive line vibrations. Make sure nothing is running on master cylinder or anything. After I put my intake on my Saturn it did that because it was rubbing on the master cylinder. Check for wheel cylinder leaks as well.