1989 190e brakes pulsate @ slow speed

[gbuford]

i have a 1989 190e that i got from my brother for my kid. as soon as i got in it to drive to Ohio from DC i noticed in his parking lot that the brakes would pulsate at slow speeds 15 mph or slower. i didn't realize then that the brake system was also making a noise like it was actuating.
well anyway i asled him about the pulsating and he said it had done it since almost day one when he bought it new.

i have recently been trying to figure out the exact culprit of this problem so i can fix it once and for all. i put new brakes and rotors on and it really didn't change things much if at all, but i have noticed wahat sounds like a pump cycling off and on when riding around at slow speed with the radio off.
this pump makes a whirring or whooshing sound that corresponds to the brake pulsation i think.

buttt what part is it that is making this pump switch on and off at slow speed???
i don't have a problem replacing it i just need to know what "IT" is lol

thanks all
gordon

[klaus kallas]

The most likely culprit is the wheel speed sensors. They are located at the brake calipers on each front wheel and run (black cable) to a connector near the ABS unit on the drivers side front fender apron.

Their purpose is to activate the ABS at the correct panic-stop times but when bad they will do it at low speeds. It can feel very unnerving! They are easy to replace, but before you do you can try cleaning the ends of them (at the caliper) as they tend to build up road grime and give false readings.

Good luck!

Klaus