Chevrolet Silverado / GMC Sierra. Manual — part 2225
Radio/Navigation System Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Navigation System Description and Operation
Electrical Information Reference
Circuit Testing
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. Ignition OFF, allow the navigation display to cool if the ambient temperature inside the
vehicle is excessive and the radio is hot to the touch. Verify the navigation display is cool
and the DTC has cleared and gone to history.
2. Ignition ON, with a scan tool, clear all DTCs and operate the audio/navigation system
within the Conditions for Running the DTC. Verify the DTC does not reset.
If the DTC resets, replace the radio.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for Radio replacement, setup, and programming
DTC B2476 OR B2482
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis
Silverado, Sierra & Silverado
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC B2476 00
Cellular Phone Select Service Switch
DTC B2482 00
Cellular Phone Select Service Switch Range/Performance
Diagnostic Fault Information
Circuit/System Description
The OnStar® button assembly consists of 3 buttons, Call/Answer, OnStar® Call Center, and
OnStar® Emergency. The communication interface module (CIM) supplies the OnStar® button
assembly with 10 volts via the keypad supply voltage circuit. Each of the buttons, when pressed,
completes the circuit across a resistor allowing a specific voltage to be returned to the CIM over
the keypad signal circuit. Depending upon the voltage range returned, the CIM is able to identify
which button has been activated.
Conditions for Running the DTC
Ignition ON.
Battery voltage must be between 9-16 volts.
Circuit
Short to
Ground
Open/High
Resistance
Short to
Voltage
Signal
Performance
Keypad Supply Voltage
B2476 00
B2476 00
B2476 00
-
Keypad Green LED Signal
1
1
2
-
Keypad Red LED Signal
1
1
2
-
Keypad Signal
3
3
-
-
Inside Rearview Mirror
Ground
-
1
-
-
1. OnStar® LED Inoperative
2. LED Illuminated At All Times
3. OnStar® Buttons Inoperative
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis
Silverado, Sierra & Silverado
Conditions for Setting the DTC
B2476
The CIM detects a short to voltage, short to ground, or an open/high resistance on the keypad
supply voltage circuit.
B2482
The CIM detects a valid signal on the keypad signal circuit for longer than 15 seconds. If one of
the OnStar® buttons is held or stuck for 15 seconds or greater, the CIM will set this DTC.
Action Taken When the DTC Sets
The OnStar® status LED turns red.
No calls can be placed.
The CIM will ignore all inputs from the OnStar® button assembly.
Conditions for Clearing the DTC
The condition responsible for setting the DTC no longer exists.
A history DTC will clear once 100 consecutive malfunction-free ignition cycles have
occurred.
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
Connector Repairs
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
Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the inside rearview mirror.
2. Ignition ON, test for 9.8-10.2 volts between the keypad supply voltage circuit terminal 12
and ground.
If less than the specified range, test the supply voltage circuit for a short to ground or
open/high resistance. If the circuit tests normal, replace the CIM.
If greater than the specified range, test the supply voltage circuit for a short to voltage.
If the circuit tests normal, replace the CIM.
3. Test for 0 volt between the keypad signal circuit terminal 11 and ground.
If greater than the specified range, test the keypad signal circuit for a short to voltage.
If the circuit tests normal, replace the CIM.
4. Test for 9.8-10.2 volts between the keypad supply voltage circuit terminal 12 and the
keypad signal circuit terminal 11.
If less than the specified range, test the keypad signal circuit for an open/high
resistance. If the circuit tests normal, replace the CIM.
5. Test for less than 5 ohms between the mirror ground circuit terminal 8 and ground.
If greater than the specified range, test the ground circuit for an open/high resistance.
6. Ignition OFF, disconnect the CIM X1 connector. Test for infinite resistance between the
keypad signal circuit terminal 11 and ground.
If less than the specified range, test the keypad signal circuit for a short to ground.
7. If all circuits test normal, test or replace the button assembly.
Component Testing
1. Ignition OFF, disconnect the harness connector at the inside rearview mirror.
2. Test for infinite resistance between the keypad supply voltage terminal 12 and the keypad
signal terminal 11.
If less than the specified range, replace the inside rearview mirror.
3. Test for 1.4k-1.6k ohms between the keypad supply voltage terminal 12 and the keypad
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis
Silverado, Sierra & Silverado
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