ABS unit activating in non-skid conditions

[chessy56]

I was reading an interesting post by "LJ" on a speedo issue which pegs at 100 mph. It seems that there was some interconnection with the ABS unit. Lately, my '01 2500HD has been experiencing some ABS related issues in which it feels like the ABS unit is activating when I lightly hit the brake around town. It's intermittent, but even when traveling ~25 mph on side streets approaching an intersection or pulling out of my driveway, I can feel the ABS unit kick in- the stiffness in the brake pedal diminishes- but the truck will still stop if I press more firmly on the pedal.

Anyone experience such an issue with the earlier Dmax/Silverados? Is there also a sensor on the tail end of the tranny which may come into play? The ABS unit itself? The truck does have 291K on it- maybe it's just getting old (like the rest of us).....

[JohnC]

There is a service bulletin covering this. Rust gets under the bracket holding the wheel speed sensor to the front hub causing a false speed reading.

[crafty]

Mine is being repaired for this same problem. There was a recall many years ago about the low speed sensors and this is likely the same thing occurring again. The mechanic said it should not mean replacing the wheel bearing unless that is bad too.

[More Power]

Might not be a bad idea for truck owners living in the traditional "rust belt" states to have a look at the wheel speed sensors now and then. Montana is somewhat more friendly to areas of the truck like wheel hubs, but I have seen some pretty crusty sensor wheels. Jim

[chessy56]

Looks like my front brake calipers are shot- too much slop around the slide pins. While I've got these off, I'll have a look for a bracket holding the sensor on (although I thought this was built into the bearing/hub assembly on the front end). Anyway, it's worth a look as long as I've got some of this apart.

Thanks for the tips guys!

[DmaxMaverick]

The sensor is mounted into the hub, on the inboard side on top, and held in place by one small bolt (threaded into the hub housing) through the plastic tab. Just follow the wire harness to the sensor (there's only one harness to each hub). The only bracket secures the harness and connector.