Noise Diagnosis - 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 reduced reception.
^ Always use a braided ground strap when applying 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 varying the following techniques:
^ Try adding the 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 a chassis ground.
^ Add a ground strap to both ends of the tape.

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 induced from a switch operation, perform one or more of the following capacitor applications, 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 mF (50 V) capacitor GM PIN 1227895
- 0.47 mF capacitor GM PIN 1227894
- Fuse block capacitor
- Feed through capacitor GM P/N 477371
- Filter package GM P/N 1224205
- Turn signal suppression
- Fuel pump suppressor GM P/N 25027405
- 21 inch braided ground strap
- 19 inch braided ground strap M P/N 6286800
- 10.5 inch braided ground strap GM P/N 6287160
- 8.5 inch braided ground strap GM P/N 12091511