I'm gonna assume he's talking about the tire pressure module.
There isn't one,I know my wifes '04 impala LS calculates rolling resistance via the ABS sensors using the ABS module I assume.
Either that or the ABS sensor's are an input to the BCM which then communicate to the message center.
If you mean the PCM,powertrain control module,then it is inside the airbox under/behind the air filter(3.8)