Chevrolet Silverado / GMC Sierra. Manual

refer to Digital Radio Signal Circuit Malfunction.

Circuit/System Testing

Digital Radio Antenna Circuit Malfunction

1. Ignition OFF, disconnect the digital radio antenna coax from the digital radio receiver

(DRR). Connect the EL-48028 to the DRR. See Special Tools.

2. Ignition ON, radio tuned to XM, verify XM reception is clear and uninterrupted.

If reception is not clear, replace the DRR.

3. Ignition OFF, disconnect the digital radio antenna coax from the digital radio antenna.

4. Ignition ON, test for less than 1 volt between the antenna coax center terminal and ground.

If greater than the specified range, replace the antenna coax.

5. Test for infinite resistance between the antenna coax center terminal and ground.

If less than the specified value, replace the antenna coax.

6. Test for less than 5 ohms of resistance on the antenna coax center circuit from end to end.

If greater than the specified range, replace the antenna coax.

7. Test for infinite resistance between the coax center terminal and the outer shield.

If less than the specified value, replace the antenna coax.

8. If all circuits test normal, test or replace the digital radio antenna.

Digital Radio Signal Circuit Malfunction

1. Ignition OFF, disconnect the X2 harness connector at the radio.

2. Radio ON, test for 5.0-7.5 volts between the signal circuit terminal 1 and ground.

If greater than the specified range, test the signal circuit for a short to voltage. If the
circuit tests normal, replace the DRR.

If less than the specified range, test the signal circuit for a short to ground or an
open/high resistance. If the circuit tests normal, replace the DRR.

3. Test for 5.0-7.5 volts between the signal circuit terminal 2 and ground.

If greater than the specified range, test the signal circuit for a short to voltage. If the
circuit tests normal, replace the DRR.

If less than the specified range, test the signal circuit for a short to ground or an
open/high resistance. If the circuit tests normal, replace the DRR.

4. Test for 5.0-7.5 volts between the signal circuit terminal 9 and ground.

If greater than the specified range, test the signal circuit for a short to voltage. If the

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

circuit tests normal, replace the DRR.

If less than the specified range, test the signal circuit for a short to ground or an
open/high resistance. If the circuit tests normal, replace the DRR.

5. Test for 5.0-7.5 volts between the signal circuit terminal 10 and ground.

If greater than the specified range, test the signal circuit for a short to voltage. If the
circuit tests normal, replace the DRR.

If less than the specified range, test the signal circuit for a short to ground or an
open/high resistance. If the circuit tests normal, replace the DRR.

6. If all circuits test normal, test or replace the radio.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Mobile Telephone Digital Antenna Replacement

Control Module References for radio or DRR replacement

DIGITAL RADIO RECEIVER SETUP

XM™ Activation

1. Radio ON, tune to the XM™ channel 0 and record the radio ID. The radio ID will be

required for activation of the new receiver.

2. Call XM™ radio to deactivate the faulty receiver and activate the new receiver.

US: 1-800-556-3600

Canada: 1-877-438-9677

3. Park the vehicle outside in an area with an unobstructed view of the southern sky.

4. Leave the vehicle outside with the ignition switch in the ACC position and the radio ON for

30 minutes to activate XM™ service.

5. Once activated, the radio will receive the remaining XM™ channels.

ONSTAR GLOBAL POSITIONING SYSTEM (GPS) DATA NOT CURRENT OR INACCURATE

Diagnostic Instructions

IMPORTANT: After replacement of an XM™ receiver, call XM™ radio to

deactivate the receiver that has been removed from the vehicle.
The vehicle must be parked in view of a satellite within 24 hours
after an activation call.

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The navigation antenna is connected to the vehicle communication interface module (VCIM) with
a RG-174 coax cable. The VCIM polls the data from the navigation antenna once every second.

Diagnostic Aids

The GPS signal title on the scan tool will display a Yes or No dependant upon whether or
not the module sees an increment of the seconds transmitted by GPS signals to the vehicle
communication interface module. Upon entering this screen, the GPS signal title will
automatically display Yes, regardless of the presence of time increment, for at least 2
seconds, while the algorithm in the scan tool determines the status of the clock. If increment
is found, Yes is continually displayed. If the clock remains static, No is displayed. The scan
tool looks for increment every second, regardless of current display.

Inaccurate or aged GPS position concerns which are no longer present may have been due
to the temporary loss of GPS signal reception by the vehicle. Conditions such as driving
through tunnels or parking structures while making an OnStar® keypress will restrict the
navigation antenna from a clear view of the satellites in the sky and may have caused this
temporary data loss.

Reference Information

Schematic Reference

OnStar Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Observe the scan tool GPS Signal Status Indicator parameter for at least 10 seconds. Verify

the indicator displays Yes.

If the indicator does not display Yes, refer to Circuit / System Testing.

2. Call and verify the OnStar advisor receive GPS data.

If the advisor did not receive GPS data and the call was a 'fail to voice', contact the
GM Technical Assistance Center.

If the advisor did not receive GPS data and the call was not a 'fail to voice', refer to
Circuit / System Testing.

3. Verify with the OnStar Call Center advisor that your actual position is within a reasonable

distance from the actual location of the vehicle.

If your actual position is not within a reasonable distance from the actual location of
the vehicle, replace the VCIM.

Circuit/System Testing

1. Ignition OFF, disconnect the navigation antenna coax from the VCIM module and the

navigation antenna.

2. Ignition ON, test for less than 1 volt between the antenna coax center terminal and ground.

If greater than the specified range, replace the antenna coax.

3. Test for infinite resistance between the antenna coax center terminal and ground.

If less than the specified value, replace the antenna coax

4. Test for less than 5 ohms of resistance at the antenna coax connector outer shield from end

to end.

If greater than specified value, replace the antenna coax cable.

IMPORTANT: Vehicle may be equipped with sectioned coax. Test each section

and replace only the faulty section, not the entire length or coax.

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

Content .. 2227 2228 2229 2230 ..

Chevrolet Silverado / GMC Sierra. Manual - part 2229