Test Description

WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number in the diagnostic table.

16. The primary HVAC control module controls the coolant bypass valve. It receives a Class 2 message from the auxiliary HVAC control module for the proper position of valve.

Fig 1: Diagnostic System Check - Too Cold in Vehicle - Auxiliary (1 Of 2)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Diagnostic System Check - Too Cold in Vehicle - Auxiliary (2 Of 2)

Courtesy of GENERAL MOTORS CORP.