Chevrolet Silverado / GMC Sierra. Manual — part 2232

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, command the Green LED ON and OFF with a scan tool while observing the

green LED on the inside rearview mirror. The green LED should turn ON and OFF when
commanded.

2. Command the red LED ON and OFF with a scan tool while observing the red LED on the

inside rearview mirror. The red LED should turn ON and OFF when commanded.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the inside rearview mirror.

2. Doors closed, courtesy lamps OFF, test for less than 5 ohms between the ground circuit

terminal 8 and ground.

If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, command the green LED OFF with a scan tool. Test for less than 1 volt

between the control circuit terminal 14 and ground.

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

4. Command the green LED ON with a scan tool. Test for greater than 9 volts between the

control circuit terminal 14 and ground.

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

5. Command the red LED OFF with a scan tool. Test for less than 1 volt between the control

circuit terminal 15 and ground.

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

6. Command the red LED ON with a scan tool. Test for greater than 9 volts between the

control circuit terminal 15 and ground.

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

7. If all circuits test normal, replace the inside rearview mirror.

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Inside Rearview Mirror Replacement

Control Module References for CIM replacement, setup, and programming

ONSTAR CALL CENTER REMOTE FUNCTION REQUESTS INOPERATIVE

Diagnostic Instructions

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 vehicle communication interface module (VCIM) has the capability of commanding the horn,
initiating door lock/unlock and operating the exterior lamps using the serial data circuits.

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

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

Scan Tool Reference

Control Module References

Diagnostic Aids

The customer concern may have been due to a lack of cellular service in a given area. A failure in
the National Cellular Network infrastructure that has since been corrected.

Circuit/System Verification

1. Observe that the horn, lights, and the doors locks on the vehicle operate properly.

If the applicable system does not operate properly, refer to Diagnostic Starting Point
- Horns , Symptoms - Lighting , or Symptoms - Remote Functions - Doors
respectively.

2. Contact the OnStar® Call Center by pressing the blue OnStar® button. Verify with the

OnStar® advisor that all of the remote functions (door locks, lights, or horn) work.

If the remote functions do not work, use the scan tool to access the STID and ESN and
contact the General Motors Technical Assistance Center.

ONSTAR ONE OR MORE BUTTONS INOPERATIVE

Diagnostic Instructions

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.

Diagnostic Fault Information

IMPORTANT: It is necessary to inform the OnStar® Call Center advisor that this

call is for vehicle diagnostic purposes.

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

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

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.

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

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

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