A few months ago I had an issue where, normally when I was pulling out of the driveway to go to work, the ABS would make a loud groaning noise and the HUD would alternate between the ABS and traction control messages.

Being under warranty, I took it to a GM dealer and they replaced the front right hub and harness. Plausible solution, quick and easy.

Ever since, the ABS will make a slightly quieter groaning noise, but pretty much only when the car is cold such as first thing in the morning or when I leave work. Stop at the store for 30 min? Not a problem. Spend three hours at a bar watching the game? Yeah, it happens.

I just got my car back after its fourth visit to the dealer. It still happens. So far they have replaced all of the ABS hubs and harnesses, along with a bonus left tie rod end (lol 44k miles?). Since it is the same issue I haven't had to pay another deductible, but it is annoying to have to keep taking it back and them not fix it.

So I experimented a bit, trying different things:

1. Doesn't matter if I use the parking brake or not (thought maybe the brakes weren't releasing all the way).
2. If I put it in neutral, rev the engine, coast down the driveway/parking lot/whatever, doesn't happen. The second I put it in either drive or reverse, it happens about one second later.
3. Doesn't matter if I idle in gear or use a little gas, same thing.
4. If I pump the brakes in park or neutral first, doesn't affect anything.
5. Once this occurs, there are no ABS or traction control issues driving no matter how hard I brake, turn, etc. It drives like a champ.

I'm starting to think maybe this has something to do with either the ABS module itself, the power brakes, or even the transmission. There has to be a sensor somewhere that is slightly out of whack (when I get a code, it is too general for GM to know what specific part is the issue), or some component that is wearing out just enough to cause this issue.

While this is harmless right now, my concern is this will become a huge expense once the warranty expires. Any ideas? This is a 2006 base model with the sport package, no customizations.