* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/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 communication interface
module (CIM) 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 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 V.
Conditions for Setting the DTC
B2476 04
The CIM detects an open/high resistance on the keypad supply voltage circuit.
B2482 and B2476 59
The CIM 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 CIM will set this DTC.
Action Taken When the DTC Sets
* The OnStar(R) status LED turns red.
* No calls can be placed.
* The CIM 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 (See: Accessories and Optional Equipment/Diagrams/Electrical Diagrams/OnStar Schematics)
Connector End View Reference
