Diagnostic Aids

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Aids
WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  • If the OnStar® Call Center has not received any GPS data, this is an indication that the OnStar® call was a fail to voice and may be due to a failure in the National Cellular Network infrastructure. If this occurs, contact the General Motors Technical Assistance Center.
  • Inaccurate or aged GPS position concerns made by a customer which are no longer present may have been due to the temporary loss of GPS signal reception by the vehicle. Conditions such as driving through tunnels or parking structures while making an OnStar® key press will restrict the navigation antenna from a clear view of the satellites in the sky and may have caused this temporary data loss.
  • Fig 1: Global Positioning System (GPS) Data Not Current Or Inaccurate Diagnosis (Steps 1-6)
    G01712597Courtesy of GENERAL MOTORS CORP.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.