Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2005 Isuzu Ascender, 2005 GMC Envoy XUV, 2005 GMC Envoy XL, 2005 GMC Envoy, and 2005 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

The customer concern may have been due to a lack of cellular service in a given area or a failure in the National Cellular Network infrastructure that has since been corrected.

OnStar® Call Center Remote Function Requests Inoperative

Step	Action	Yes	No
Schematic Reference: OnStar® Schematics Connector End View Reference: Cellular Communication Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Attempt to honk the horn, operate the lights, and lock or unlock the doors on the vehicle. Does the applicable system operate properly?	Go to Step 3	Go to Diagnostic Starting Point - Horns in Horns Go to Diagnostic Starting Point - Lighting Systems in Lighting Systems Go to Diagnostic Starting Point - Doors in Doors
3	IMPORTANT: It is necessary to inform the OnStar® Call Center advisor that this call is for vehicle diagnostic purposes. Contact the OnStar® Call Center by pressing the blue OnStar® button. Ask the OnStar® advisor to perform a remote function (door lock/unlock, light flash, or horn honk). Was the attempt successful?	Go to Diagnostic Aids	Use the scan tool to access the STID and ESN and contact the General Motors Technical Assistance Center