LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Hummer >> 2008 >> H3 Base, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 168 (Cellular System, Entertainment System, And Navigation System) >> Diagnostic Information and Procedures >> Radio Poor Reception >> Circuit/System Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Circuit/System Testing

WARNING: This page is about a different car, the 2008 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.

Antenna Coaxial Cable Testing

    IMPORTANT: For steps 2-5, perform the tests on each of the disconnected coax cables.
  1. Ignition OFF, disconnect all coax cables from the radio, radio antenna modules, and both antennas in the left and right rear windows.
  2. Test for infinite resistance between the antenna coax center terminal and ground.
    • If less than the specified value, replace the antenna coax.
  3. Test for less than 5 ohms on the antenna coax center terminal from end to end.
    • If greater than the specified range, replace the antenna coax.
  4. Test for less than 5 ohms on the antenna coax outer shield from end to end.
    • If greater than the specified range, replace the antenna coax.
  5. Test for infinite resistance between the coax center terminal and the outer shield.
    • If less than the specified value, replace the antenna coax.

Antenna Inspection

  1. Ignition OFF, disconnect the coax cables from the antennas located in the left and right rear windows.
  2. Verify the coax connectors are properly secured and free of any damage.
    • If damage is found, repair or replace as necessary.
  3. Inspect each antenna. Verify all branches of the antennas are intact, with no scratches or other damage.
    • If damage is found, repair or replace as necessary.

Radio Antenna Module Test

  1. Inspect the radio antenna module grounding surface and the mounting hardware for any corrosion that may cause a poor ground.
    • If corrosion is noted, clean the grounding surfaces and hardware.
  2. Ignition OFF, disconnect the X3 harness connector at the radio antenna module.
  3. Radio ON, test for B+ between the signal circuit terminal A and ground.
    • If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.
  4. If all circuits test normal, replace the radio antenna module.