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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1127 (Horn System) >> Diagnostic Information and Procedures >> Horns Malfunction >> Component Testing

Component Testing

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

Horn Test

  1. Ignition OFF, disconnect the harness connector at the horn assembly.
  2. Install a 15A fused jumper wire between the control terminal B and 12 volts. Install a jumper wire between the ground terminal A and ground. Verify the horns emit a clear and even tone.
    • If the sound emitted is not clear and even, replace the horn assembly.

Relay Test

  1. Ignition OFF, disconnect the HORN relay.
  2. Test for 60-180 ohms between terminals 85 and 86.
    • If not within the specified range, replace the relay.
  3. Test for infinite resistance between the following terminals:
    • 30 and 86
    • 30 and 87
    • 30 and 85
    • 85 and 87
    • If not the specified value, replace the relay.
  4. Install a 30-amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87.
    • If greater than the specified range, replace the relay.
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