For 1990-2009 cars only
Diagnostic Instructions
| • | 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. |
Circuit/System Description
The vehicle communication interface module (VCIM) has the capability of commanding the horn, initiating door lock/unlock and operating the exterior lamps using the serial data circuits.
Reference Information
Schematic Reference
Connector End View Reference
Entertainment/Communication Connector End Views
Description and Operation
OnStar Description and Operation
Electrical Information Reference
Scan Tool Reference
Diagnostic Aids
The customer concern may have been due to a lack of cellular service in a given area. A failure in the National Cellular Network infrastructure that has since been corrected.
Circuit/System Verification
Important: It is necessary to inform the OnStar® Call Center advisor that this call is for vehicle diagnostic purposes.
- Observe that the horn, lights, and the doors locks on the vehicle operate properly.
- Contact the OnStar® Call Center by pressing the blue OnStar® button. Verify with the OnStar® advisor that all of the remote functions (door locks, lights, or horn) work.
| ⇒ | If the applicable system does not operate properly, refer to Diagnostic Starting Point - Horns , Diagnostic Starting Point - Lighting , or Symptoms - Remote Functions respectively. |
| ⇒ | If the remote functions do not work, use the scan tool to access the STID and ESN and contact the General Motors Technical Assistance Center. |
