B2482

DTC B2476 or B2482

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptors
DTC B2476 04
- Cellular Phone Select Service Switch Open Circuit

DTC B2476 59
- Cellular Phone Select Service Switch Stuck Button

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

Diagnostic Fault Information





Circuit/System Description

The OnStar(R) button assembly consists of 3 buttons, Call/Answer, OnStar(R) Call Center, and OnStar(R) Emergency. The telematics communication interface control module supplies the OnStar(R) button assembly with 10 V 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 telematics communication interface control module over the keypad signal circuit. Depending upon the voltage range returned, the telematics communication interface control module is able to identify which button has been activated.

Conditions for Running the DTC

* Ignition ON.
* Battery voltage must be between 9-16 V.

Conditions for Setting the DTC

B2476 04

The telematics communication interface control module detects an open/high resistance on the keypad supply voltage circuit.

B2482 and B2476 59

The telematics communication interface control module detects a valid signal on the keypad signal circuit for longer than 15 seconds. If one of the OnStar(R) buttons is held or stuck for 15 seconds or greater, the telematics communication interface control module will set this DTC.

Action Taken When the DTC Sets

* The OnStar(R) status LED turns red.
* No calls can be placed.
* The telematics communication interface control module will ignore all inputs from the OnStar(R) button assembly.

Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Reference Information
Schematic Reference

OnStar Schematics (OnStar Schematics)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

OnStar Description and Operation (OnStar)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the A10 inside rearview mirror.
2. Test for less than 15 Ohms between the mirror ground circuit terminal 5 and ground.

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

3. Ignition ON, test for less than 1 V between the keypad signal circuit terminal 3 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 K73 telematics communication interface control module.

4. Ignition OFF, test for 600k-850k Ohms between the keypad signal circuit terminal 3 and ground.

• If less than the specified range, test the keypad signal circuit for a short to ground. If the circuit tests normal, replace the K73 telematics communication interface control module.
• If greater than the specified range, test the keypad signal circuit for an open/high resistance. If the circuit tests normal, replace the K73 telematics communication interface control module.

5. Ignition ON, test for 9.5-10.5 V between the keypad supply voltage circuit terminal 4 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 K73 telematics communication interface control module.
• If greater than the specified range, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the K73 telematics communication interface control module.

6. If all circuits test normal, test or replace the button assembly.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Inside Rearview Mirror Replacement (Inside Rearview Mirror Replacement)
* Control Module References (Programming and Relearning) for telematics communication interface control module replacement, setup and programming