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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 111 (Horn System) >> Diagnostic Information and Procedures >> Horns Inoperative >> Circuit/System Testing

Circuit/System Testing

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  1. Ignition OFF, test for less than 1.0 ohm of resistance between each horn ground circuit terminal A and ground.
    • If greater than 1.0 ohm, test the ground circuit for an open/high resistance.
  2. If the HORN fuse in the underhood fuse block is open, disconnect the horns and test the horn control circuit for a short to ground.
    • If the circuit tests normal, reconnect one horn and retest the circuit.
    • If the circuit tests normal again, replace the disconnected horn. If a short to ground is now present, replace the connected horn.
  3. Test for voltage at the horn connectors.
    • If voltage is present, replace the horns.
  4. Test the horn control circuit for an open or high resistance.
  5. Ignition OFF, disconnect the underhood fuse block connector C4.
  6. Activate the horn switch while testing for a ground signal at the horn relay control terminal G1 of the disconnected underhood fuse block harness connector.
    • If a ground signal is present, replace the underhood fuse block.
    7. IMPORTANT: The horn switch is located under the inflatable restraint steering wheel module. To disable the SIR system refer to SIR Disabling and Enabling .
  7. Disconnect the horn switch and test the switch for proper continuity.
    • If the switch does not function properly, replace.
  8. Test for an open or high resistance in the horn relay control circuit and the horn switch ground circuit.
    • If the circuits/connectors test normal, replace the inflatable restraint steering wheel module coil.
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