Circuit/System Testing
- Ignition OFF, disconnect the GPS and cell coax cable connector at the vehicle communication interface module.
- Using the EL-49903 - 3 kit (EL-49903 - 5 adapter and EL-49903 - 4 coax cable), connect the EL-49903 GM OnStar antenna diagnostic tool kit to the vehicle communication interface module, place the test antenna on the roof of the vehicle.
- Ignition ON, wait 5 minutes, then contact the OnStar call center consultant by pressing the blue OnStar button. A call center consultant should answer the call, ask the consultant to verify the vehicle location to confirm the GPS system is functioning.
- If the OnStar GPS does not function, replace the vehicle communication interface module.
- Reconnect the coax cable to the vehicle communication interface module. Disconnect the coax cable from the radio antenna.
- Test for 4.5 - 5.5 V between the coax cable center conductor and the outer shield.
- If not within the specified range, replace the coax cable.
- If all circuits test normal, replace the radio antenna.