Diagnostic Instructions
Circuit/System Description
The vehicle communication interface module (VCIM) has the capability of commanding the horn and initiating door lock/unlock. These functions are commanded by the OnStar® Call Center per a customer request.
Diagnostic Aids
The customer concern may have been due to a lack of cellular service in a given area.
Reference Information
Schematic Reference
OnStar Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
OnStar Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Important:
• | When contacting the OnStar Call Center, explain to the OnStar advisor that this call is for vehicle diagnostic purposes. |
• | It is necessary to have the vehicle in an open outside area where a cellular call can be successfully placed and GPS data can be received from satellites. |
- Verify 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 and horn)work.
⇒ | If the door locks do not operate when requested, refer to Remote Door Locks Malfunction. |
- If the horn does not operate when requested, refer to Remote Horn Malfunction.
Circuit/System Testing
Remote Door Locks Malfunction
- Ignition OFF, disconnect the harness connector at the OnStar interface module.
- Ignition ON, test for less than 1 volt between the signal circuit terminal 3 and ground.
⇒ | If greater than the specified range, test the signal circuit for a short to voltage. |
- Test for infinite resistance between the signal circuit terminal 3 and ground.
⇒ | If not the specified value, test the signal circuit for a short to ground. |
- If all circuits test normal, replace the OnStar interface module.
Remote Horn Malfunction
- Ignition OFF, disconnect the harness connector at the OnStar interface module.
- Ignition ON, test for less than 1 volt between the signal circuit terminal 4 and ground.
⇒ | If greater than the specified range, test the signal circuit for a short to voltage. |
- Test for infinite resistance between the signal circuit terminal 4 and ground.
⇒ | If not the specified value, test the signal circuit for a short to ground. |
- If all circuits test normal, replace the OnStar interface module.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for OnStar integration module replacement, setup, and programming