Chevrolet Silverado / GMC Sierra. Manual — part 2227
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the
symptom:
Speaker Malfunction
Radio Audio Inoperative at Rear Seat Audio (RSA) Control
Radio Displays LOC, LOCKED, or CODE
Radio Displays CAL or CAL ERR
Radio Poor Reception
Radio Controls Inoperative - Rear Seat
Video Display is Poor or Blank
Video Entertainment System Inoperative
Video Entertainment System Remote Control Inoperative
Video Entertainment System Wireless Headphone Inoperative
SYMPTOMS - NAVIGATION SYSTEMS
Perform the Diagnostic System Check - Vehicle before using the symptom tables in order
to verify that all of the following are true:
There are no DTCs set.
The control modules can communicate via the serial data link.
Review Navigation System Description and Operation in order to familiarize yourself
with the system functions.
Visual/Physical Inspection
Inspect for aftermarket devices which could affect the operation of the navigation system
components. Refer to Checking Aftermarket Accessories .
Inspect the easily accessible or visible system components for obvious damage or conditions
which could cause the symptom.
Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to
IMPORTANT: The following steps must be completed before using the symptom
tables.
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis
Silverado, Sierra & Silverado
Testing for Intermittent Conditions and Poor Connections .
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the
symptom:
No Global Positioning System (GPS) Reception
For radio/audio related symptoms, refer to Symptoms - Entertainment.
AUDIO SYSTEM TROUBLESHOOTING HINTS
Many conditions that affect radio operation may be corrected without removing the radio from
the car. Verify the condition, and follow the diagnostic procedures in order to isolate and correct
the condition. In order to properly diagnose any audio system problems, ensure that you have a
fully charged battery.
Preliminary Inspections
Check for any aftermarket equipment that may have been installed on the vehicle. If
aftermarket equipment is found disconnect it and check if the audio noise is still present.
Inspect that the antenna connector and the antenna coaxial cable are clean and tight.
For reception concerns, first determine if the customer is within the listening area of the
stations they are attempting to receive.
Stations at the lower end of the FM band are more susceptible to audio noises than stations
at the higher end.
If the noise is only from one speaker check for the following before speaker replacement:
Isolate the noise using the J 39916-A CD and Cassette Diagnostic Audio Kit. See
Special Tools.
Inspect the speaker connections to ensure they are clean and tight. Refer to Testing
for Intermittent Conditions and Poor Connections .
Inspect for a loose or incorrectly installed speaker or surrounding trim. Loose trim can
cause a buzz or flutter which sounds like a malfunctioning speaker.
Ignition noise on the FM band may be an indication of an ignition system problem.
IMPORTANT: When testing the audio system for poor reception or noise,
the vehicle should be outside away from metal buildings and
utility lines, with the hood and rear compartment closed.
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis
Silverado, Sierra & Silverado
Inspect that all vehicle grounds are clean, tight and free of corrosion.
Inspect the rear defogger grid lines for large breaks or dark spots.
Inspect the connections at the radio antenna module, if equipped, to ensure that they are
clean and tight.
Compare the customers vehicle to another of similar model and audio system to determine if
the condition is abnormal.
Identifying Concerns
1. In order to isolate the source of the noise/poor reception, identify the ignition switch
position that the concern is most noticeable:
1. Turn the ignition switch to the accessory position.
2. Turn ON the radio.
3. Seek up 88-108 FM then 550-1600 AM.
4. Record the number of valid radio stations where the tuner stops.
5. Repeat these steps with the ignition ON, and the engine OFF then again with the
engine running.
2. Return the ignition switch to the position that the concern was most noticeable.
3. Remove fuses or circuit breakers one at a time until the noise has been eliminated.
4. Identify what systems or components are powered by the fuse.
5. Reinstall all fuses and circuit breakers.
6. Disconnect the components powered by the fuse one at a time until the concern has been
eliminated.
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. Attempt variations of
the following repairs:
Add only aluminum or nickel tape before adding a ground strap to the tape.
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis
Silverado, Sierra & Silverado
Wrap a ground strap 360 degrees around the tape, securing the other end of the
strap to chassis ground.
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 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 (50 V) capacitor GM P/N 1227895-Works well for ignition system
related noise.
0.47 micro farad capacitor GM P/N 1227894-Works well for switches and relays.
Feed through capacitor GM P/N 477371-Works well for high current situations.
Filter package GM P/N 1224205-Works well for low current situations.
Fuel pump suppressor GM P/N 25027405
53.34 cm (21 in) braided ground strap GM P/N 8910791
48.26 cm (19 in) braided ground strap GM P/N 6286800
26.67 cm (10.5 in) braided ground strap GM P/N 6287160
21.59 cm (8.5 in) braided ground strap GM P/N 12091511
Generator Whine Concerns
1. Inspect the ground terminal and cable for high resistance.
2. Inspect the generator and brackets for loose or coated mounting bolts.
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.
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis
Silverado, Sierra & Silverado
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