Originally Posted by weasel56

If I am remembering correctly, the tire pressure monitor on the early E53's reads the wheel speed sensors, and reads them through communication with the DSC module. I seem to remember the TPM module as a small white box about the size of a pack of cigarettes, maybe you could look up the location and wiring schematics in the online WDS link at the top of the page. If only all dealers/techs/advisers had the brain power to diagnose something other than part replacement...