Where is the brain box located on 06 Pontiac g6 gtp? How do you know if that's the problem?

Are you having performance problems, or are you trying to customize something? on this car, it's either on the firewall, or under the passenger seat, just guesses as the last time we (as my team of mechanics tried to deal with this, we replaced the brain box thrice (no returns on electrical) to find that it was a dirty ground wire not supplying a solid connection to both frame and ground...so start with the basics before you start pickin' the brain.

The G6 should have two computers. One for the engine and one for the body. They usually are found behind/below the glove box but it might be different on the G6 since it's really an Australian Holden. --- "How do you know if that's the problem" --- what problem are you experiencing?

It's turning over but won't crank

No ignition? do you have gas in this buggy?

Got no spark....why you coulda said so!

there are a couple of factors that could cause a no spark situation, but foremost hose off the corrosion from your battery then clean the connections there (like I said at the outset), then the powered devices will have good power. Your brain will be doing it's job if it did not run into a bad crank angle sensor, for example....you want to chop off the head when all it needs is a good shave.

So on a Pontiac G6 07 the pcm is located behind the glove department?