98 GMC Envoy ABS Problem

[JimKW]

Posted this in the wrong forum:

First post here. I use Msg Boards quite a bit and did do a quck search and I know if I really searched harder I could probably find an answer, but I don't have time right now so I thought I would just ask.

In my 98 GMC Envoy, that I use primarily for towing a boat, the ABS light will come on intermittently and stay of for a while then go out. Last night it did not go out until I started backing down the boat ramp.

One time last week I was driving it without the boat and the brakes acted real strange. I was going real slow and stepped on the brakes and it felt like it was not going to stop. The brake pedal kind of pulsated and it was slowing down, but not braking like normal. Kind of hard to explain, but you could feel the ABS, but not a normal feel like you would if on a slippery road. I was on perfect dry pavement and then it happened again as I was going down the driveway with the boat on the back. It stops doing it very quickly and then the brakes seem to work fine.

If this happened on my 850 Volvo's I would think my ABS module was bad, but really don't know much about the Envoy.

[68C15]

rust jacking on the sensors causing an unintended ABS activation?

at work I would hook up my 4 channel lab scope and watch the sine wave of the sensors to see if one or more had a different amplitude.