LOCATION: Everywhere - but particularly right next to my head somewhere in the B Pillar (well that's what's annoying me at the moment) - and the dash. All of it.
WHEN: Constantly
REASON: Just another fine example of holden's billion dollars of development being let down by cost cutting in production
EASIEST WAY TO FIX: Agree with selling it.
RATTLE SOLVED
I had the exact same thing - turns out it's actually not in the B pillar.....it's coming through the floor, up through the B pillar, right next to my right ear. There is a plastic cover under the drivers' seat - it rattles under certain conditions. This cover protects three cables (one I think is the fuel line) - these cables create a buzz in my vehicle at precisely 2000rpm, as they vibrate against each other when a particular harmonic occurs. I taped these three cables together tightly and padded between the fuel tank and the plastic cover with sponge, and my rattle immediately stopped.
I spent 12 months driving around without the liner on the drivers' passenger door - took the speaker out of the door too. I even removed the plastic weather sheet, and examined the entire inside door area, and inside the B pillar - padded everything with double-sided tape and gooped everything with fish oil. I ripped out all the plastic covers on the B pillar and the kick panels. It wasn't until I pulled out the rear seat that I could finally tell that the buzz/rattle was not coming from between the B pillar and the rear dirvers' side door. I could finally hear it was coming from beneath the floor. Once I stuck my head underneath - it was obvious.
I even had the dealership spend two weeks driving my VE around trying to pin the noise down - everybody thought it was coming from around the B pillar, next to the driver's right ear BUT IT WASN'T.
If this rattle can appear to be coming from the B pillar, it can probably appear to be coming from anywhere, depending on where the cables are vibrating, and at what frequency/harmonic.
If your Commodore rattles or buzzes - try this. if this doesn't fix it, do what I did - strip the guts out of your car and you might be able to nail it. I'm so relieved I don't have to sell my Commodore - the noise was driving me mad. It made be so angry at Holden, every time drove it.
Oh - other symptoms: the rattle/buzz got better and even went away after driving over hot roads (ie: straight out of the garage it was bad, but 20 minutes down the road on a hot day - it would go away......cold days - it was worse).
I also found that the clunk at 14kph is the ABS self test, and the softer clunk at 34kph is also the ABS system. These clunks only occur first time driving off. They don't happen if you only stop for a minute, or at lights. These noises are 'normal'.