The following numbers refer to the steps in the table.
This step ensures that OnStar® can communicate with the vehicle and that the OnStar® GPS system is configured.
This step checks proper operation of the GPS. The location that you are given from the OnStar® center is only an approximate location. There can be variance in this location. Do not mistake location variance for a inoperative GPS system.
It is necessary to have a good ground on the antenna to filter out signal noise.
Step  | Action  | Value(s)  | Yes  | No  | 
|---|---|---|---|---|
DEFINITION: This procedure is to diagnose the cause of the inoperative GPS receiver.  | ||||
1  | Did you perform the OnStar® Diagnostic System Check?  | --  | Go to Step 2  | Go to OnStar System Check  | 
 Did you complete the repair?  | --  | Go to Step 2  | Go to OnStar Call Center Unable to Configure OnStar (R) System  | |
 Does the location given match you approximate location?  | --  | Go to Step 10  | Go to Step 4  | |
4  | Is the GPS antenna installed in the proper location?  | --  | Go to Step 5  | |
5  | Inspect the GPS Antenna at the headliner. Is the Grounding tab securely attached to the roof with the maximum area, as close as possible to the housing?  | Go to Step 6  | Go to Step 4  | |
6  | 
 Is the antenna cable free from damage?  | --  | Go to Step 7  | Go to Step 8  | 
Test the ground circuit of the GPS antenna for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?  | --  | Go to Step 10  | Go to Step 9  | |
8  | Replace the GPS antenna. Refer to Antenna Assembly Replacement . Is the repair complete?  | --  | Go to Step 10  | --  | 
9  | Replace the VIU. Refer to Vehicle Interface Unit and Vehicle Communication Unit Modules Replacement Is the action complete?  | --  | Go to Step 10  | --  | 
10  | Operate the system in order to verify the repair. Did you correct the condition?  | --  | System OK  | Go to Step 3  |