I'm changing one and only one this weekend.

Thanks for all the replies. I've had a few skilled mechanics take a look at the hubs, since I know they run about $90 or so and I wanted to be sure that was the issue - they said it wasn't. Alas, since it's still occurring... I'm short on cash but I always replace in pairs (usually because it's an OCD thing, nonetheless...). It just sucks that Chevy decided to put them IN the hub... what nonsense. Argh. I'll see if anyone I know has an ABS code reader.

An ABS scan tool should shed a lot of light on the subject.

Make sure the wires and connections are good (such as no animals chewed the wires). Personally, my best guess is, you'll be changing the hubs and hopefuly an ABS Scan Tool will answer that. May want to see if a dealership shop could do a free diagnostic....

You can rent or at least use in parking lot an ABS code reader from Autozone.

I believe there is a ground under the airbox that can get dirty and mess with these sensors too.

I really would verify the wiring harness is good. I had the same issues with my 2001. The abs code indicated no communication with the right front sensor so the shop said the hub would need to be replaced.
It was NOT the hub it was the harness which I checked with my ohmmeter. There was no visible damage to it but there must have been a break inside the casing. I ordered a new harness for under $40 dollars and have not had the problem since. There was also a technical service bulletin for the harness for montes, gran prixs, buicks and maybe a couple of more.
Its easy to check and fix and if the harness is bad of course the computer will throw a code because it can't talk to the sensor.

Good luck with it.

-Jim

How far up did you splice in the new wire harness? I've got to do the right front as well. The manual says to follow the wiring harness where it goes into the large conduit and splice it to the wires inside the large conduit. But that large conduit for the right side is at the front bottom of the engine. So, really hard to get to.

And did you use heat shrink butt connectors?

I went up to maybe 10" before the harness became part of the larger bundle of wires in front of the engine. Seems like most of the harness problems were closer to the control arm and wheel where it gets flexed more unless it was damaged by debris. I wrapped my splice in electrical tape and then coated that with some silicone sealant and it still looks intact after about 2 years.
I ordered the Dorman brand harness. It was plenty long and also came with the plastic clips to fasten it to the frame and control arm. I think it also came with the butt connectors too. If you order it through Rockauto.com search for my previous posts. There is a code for a 5% discount for online orders that is good until February something. Hope this turns out to be the problem. Aside from cleaning this is the cheapest fix for these issues.

Jacking up one side of the front and removing the tire gave me enough room to get the job done pretty easily.

When Mine was bad the TCS light came on only once in a while but as time went on it finally stayed on and had to be replaced.

Wow guys this has been such a huge help and an excellent hub of information! I'll check the wire harness soon, I hope that's the culprit. $40 for a harness or $180 for a pair of hubs... Yeah, I hope it's the former.


EDIT: now that I think about it, this started possibly a few weeks after I hit a very large puddle of standing water (the tires were nearly entirely submerged). Do you think... maybe...?