For 1990-2009 cars

### 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.

### DTC Descriptor

DTC B2482 00: Cellular Phone Select Service Switch Range/Performance

### Circuit/System Description

The OnStar® button assembly consists of 3 buttons, Call/Answer, OnStar® Call Center and OnStar® Emergency. Ten volts is supplied to the button assembly on the keypad supply voltage circuit. Each of the buttons, when pressed, completes the circuit across a resister allowing a specific voltage to be returned to the vehicle communication interface module (VCIM) on the keypad signal circuit. Depending upon the voltage range returned, the VCIM is able to identify which button has been pressed.

### Conditions for Running the DTC

• | The ignition must be in the RUN or ACC position.

• | The system voltage is at least 9.5 volts and no more than 15.5 volts.

• | All the above conditions are present for greater than 15 seconds.

### Conditions for Setting the DTC

• | A button is pressed or stuck for more than 15 seconds.

• | The above conditions are present for greater than 15 seconds.

### Action Taken When the DTC Sets

• | The VCIM will ignore all inputs from the OnStar® button assembly.

• | No calls can be placed.

• | The OnStar® status LED turns red.

### Conditions for Clearing the DTC

• | The button will be declared unstuck after a 50 millisecond normal cycle.

• | A history DTC clears after 50 malfunction-free ignition cycles.

### Reference Information

#### Schematic Reference

OnStar Schematics

#### Connector End View Reference

Entertainment/Communication 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

### Circuit/System Testing

1. Ignition OFF, disconnect the inside rearview mirror harness connector.
2. Test for infinite resistance between terminal 12 and 11.

⇒ | If resistance less than the specified value, replace the rearview mirror.

⇒ | If all circuits test normal, replace the VCIM

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Inside Rearview Mirror Replacement

• | Control Module References for VCIM replacement, setup, and programming