Corrective Action

• Inspect the ground integrity of the component or system causing the noise.
• Malfunctioning and marginal components such as relays and solenoids may cause noise and/or poor reception.
• Always use a braided ground strap when applying additional grounds and keep the ground strap as short as possible.
• If the noise source is found to be coming from the vehicle harness:
  • Route the antenna cable separately from the wire harness that is emitting the noise.
  • Use aluminum or nickel tape in order to shield the antenna cable. Try variations of the following repairs:
    • Try adding only aluminum or nickel tape before adding a ground strap to the tape.
    • Wrap a ground strap 360 degrees around the tape, securing the other end of the strap to chassis ground.

Important:  When installing suppression devices, signal wires such as sensor and communication circuits should not be suppressed. Battery and ignition voltage circuits are the best choices for suppressing.

• Capacitors work best on switch pops and low frequency noise.
• Filters work best on high frequency whines and static.
• After adding any suppression device, inspect all of the vehicle systems, including those not related to the audio system, for proper operation and function.
• Whenever possible, make a test harness that includes filters or capacitors. Always inspect the effectiveness and operation before permanent installation.
• If an audible pop is caused due to operating a switch, perform the following repairs as necessary:
  • Add a capacitor across the contacts of the switch.
  • Add a capacitor from the battery positive voltage (B+) side of the switch to chassis ground.
  • Add a capacitor from the ground side of the switch to chassis ground.
• Use the following available noise suppression devices:
  • 220 micro farad (50V) capacitor GM P/N 1227895

    This works well for ignition system related noise.

  • 0.47 micro farad capacitor GM P/N 1227894 This works well for switches and relays.
  • Feed through capacitor GM P/N 477371 This works well for high current situations.
  • Filter package GM P/N 1224205 This works well for low current situations.
  • Fuel pump suppressor GM P/N 25027405
  • 21 inch braided ground strap GMP P/N 8910791
  • 19 inch braided ground strap GM P/N 6286800
  • 10.5 inch braided ground strap GM P/N 6287160
  • 8.5 inch braided ground strap GM P/N 12091511