GM Service Manual Online
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.

DTC Descriptors

DTC B2483 00: GPS Sensor Circuit Low

DTC B2484 00: GPS Sensor Circuit Open

Circuit/System Description

Tthe vehicle communication interface module (VCIM) receives GPS information from a specific navigation antenna located on the outside of the vehicle. The navigation antenna is connected to the VCIM via a shielded coaxial cable. The antenna cable also provides a path for DC current for powering the antenna.

Conditions for Running the DTC

    • The ignition must be in the RUN or ACC position.
    • The system voltage is at least 9.5 volts and no more than 15.5 volts.
    • All the above conditions are present for greater than 1 second.

Conditions for Setting the DTC

B2483

The VCIM detects a short to ground on the navigation antenna signal circuit.

B2484

The VCIM detects an open/high resistance on the navigation antenna signal circuit.

Action Taken When the DTC Sets

    • The OnStar® status LED turns red.
    • The OnStar® Call Center cannot locate the vehicle.

Conditions for Clearing the DTC

    • The condition responsible for setting the DTC no longer exists.
    • A history DTC clears after 50 malfunction-free ignition cycles.

Reference Information

Schematic Reference

OnStar Schematics

Connector End View Reference

Entertainment/Communication Connector End Views

Description and Operation

OnStar Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

  1. Disconnect the navigation antenna coax connector from the VCIM.
  2. Ignition ON, test for 4.5-5.5 V between the VCIM coax cable center conductor terminal at the module and ground.
  3. If not within the specified range, replace the VCIM.
  4. Reconnect the coax cable to the CIM. Disconnect the coax cable from the navigation antenna.
  5. Test for 4.5-5.5 V between the coax cable center conductor and the outer shield.
  6. If not within the specified range, replace the coax cable.
  7. If all circuits test normal, replace the navigation antenna.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Cellular Communications/Digital Radio Antenna Replacement
    •  Control Module References for VCIM replacement, setup, and programming