GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2007 🢒 Rendezvous - FWD 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC B2476

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 B2476 00 : Cellular Phone Select Service Switch Malfunction

Diagnostic Fault Information

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

--

--

Button Assembly Ground

--

1

--

--

1. OnStar® LED(s) Inoperative

2. LED illuminated at all times

3. OnStar® Buttons Inoperative

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
    • 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 300 milliseconds.

Conditions for Setting the DTC

The CIM detects a short to voltage, short to ground, or an open/high resistance on the keypad supply voltage circuit.

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

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 harness connector at the button assembly.
  2. Ignition ON, test for 9.8-10.2 volts between the keypad supply voltage circuit terminal A and ground.
    3. ⇒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 B and ground.
    4. ⇒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 A and the keypad signal circuit terminal B.
    5. ⇒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 ground circuit terminal E and ground.
    6. ⇒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 B and ground.
    7. ⇒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 button assembly.
  2. Test for infinite resistance between the keypad supply voltage terminal A and the keypad signal terminal B.
    3. ⇒If less than the specified range, replace the button assembly.
  3. Test for 1.4k-1.6k ohms between the keypad supply voltage terminal A and the keypad signal terminal B while pressing the black phone button.
    4. ⇒If not within the specified range, replace the button assembly.
  4. Test for 2.7k-3.3k ohms between the keypad supply voltage terminal A and the keypad signal terminal B while pressing the blue On-Star® button.
    5. ⇒If not within the specified range, replace the button assembly.
  5. Test for 11.7k-14.3k ohms between the keypad supply voltage terminal A and the keypad signal terminal B while pressing the red emergency button.
    6. ⇒If not within the specified range, replace the button assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  OnStar Button Assembly Replacement
    •  Control Module References for CIM replacement, setup, and programming