Chevrolet Trax: Onstar button malfunction

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 Descriptors

DTC B2476 04

Cellular Phone Select Service Switch Open

DTC B2476 59

Cellular Phone Select Service Switch Protection Time-out

DTC B2482 00

Cellular Phone Select Service Switch Range/Performance

Diagnostic Fault Information

Circuit/System Description

The OnStar button assembly consists of 3 buttons: Call/Answer, OnStar Call Center, and OnStar Emergency. The telematics communication interface control module supplies the OnStar button assembly with 10 V via the 10 V reference 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 a short to voltage or an open/high resistance on the keypad 10 V reference circuit.

B2482 and B2476 59

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

Action Taken When the DTC Sets

• The OnStar status LED turns red.
• No calls can be placed.
• The telematics communication interface control module 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 50 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

OnStar/Telematics Schematics (Encore), OnStar/Telematics Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

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

NOTE: Contact the OnStar Call Center first before pressing the emergency button in order to notify them of the test.

1. Ignition ON.
2. Verify no DTCs are set.

• If any DTCs are set

Diagnostic Trouble Code (DTC) List - Vehicle

• If no DTCs are set

3. Verify that each button of the S51 Telematics Button Assembly operates normally by pressing each button individually.

• If none of the buttons operate normally

Refer to Circuit/System Testing

• If some, but not all, of the buttons operate normally

Test or replace the A10 Inside Rearview Mirror.

If all of the buttons operate normally

4. All OK.

Circuit/System Testing

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the A10 Inside Rearview Mirror. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal 5 and ground.

If 10 ohms or greater

1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.

If less than 10 ohms

3. Ignition ON.
4. Test for 8.0-10.5 V between the 10 V reference circuit terminal 4 and ground.

If less than 8.0 V

1. Ignition OFF, disconnect the harness connector at the K73 Telematics Communication Interface Control Module.
2. Test for infinite resistance between the 10 V reference circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance

3. Test for less than 2 ohms in the 10 V reference circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K73 Telematics Communication Interface Control Module

If greater than 10.5 V

1. Ignition OFF, disconnect the harness connector at the K73 Telematics Communication Interface Control Module, ignition ON.
2. Test for less than 1 V between the 10 V reference circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K73 Telematics Communication Interface Control Module.

If between 8.0-10.5 V

5. Ignition OFF.
6. Test for 500-900 ohms between the signal circuit terminal 3 and ground.

If less than 500 ohms

1. Disconnect the X1 harness connector at the K73 Telematics Communication Interface Control Module.
2. Test for infinite resistance between the signal circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K73 Telematics Communication Interface Control Module.

If greater than 900 ohms

1. Disconnect the X1 harness connector at the K73 Telematics Communication Interface Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V

3. Ignition OFF.
4. Test for less than 2 ohms in the signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K73 Telematics Communication Interface Control Module.

If between 500-900 ohms

7. Test or replace the A10 Inside Rearview Mirror.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Inside Rearview Mirror Replacement
• Control Module References for telematics communication interface control module replacement, programming and setup.

ONSTAR STEERING WHEEL CONTROL FUNCTIONS MALFUNCTION

Some vehicles equipped with the OnStar system have the capability of accessing voice mailboxes and other automated phone systems by means of the steering wheel controls, while the OnStar Personal Calling feature is in use. If the "Talk" or "Mute" button (depending upon the vehicle) on the steering wheel controls is depressed during an OnStar Personal Calling call, the telematics communication interface control module receives the message on the serial data bus from either the radio or body control module. This message is interpreted as a request to turn any spoken numbers into dual tone multi-frequency tones to be delivered over the airwaves to the phone system the user is communicating with. Complete instructions for operation of these features can be found in the information provided to the customer with the OnStar system.

The steering wheel controls are a resistor network that consist of multiple momentary contact switches and a series of resistors. The switches and resistor network are arranged so that each switch has a different resistance value. When a switch is pressed, a voltage drop occurs in the resistor network, which produces a specific voltage value unique to the switch selected, to be interpreted by either the radio or BCM. In the event the OnStar steering wheel control functions are inoperative, technicians should refer to Steering Wheel Controls Malfunction , to begin diagnosis of the steering wheel control concern.

READ NEXT: