Diagnostic Instructions

NOTE:

This procedure only pertains to vehicles without Onstar (RPO UE1). If CAL is displayed on vehicles with Onstar, refer to OnStar Global Positioning System (GPS) Data Not Current or Inaccurate .

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions provides an overview of each diagnostic category.