OnStar Button Malfunction
OnStar Button Malfunction
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.
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.
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 Verification
Note: Contact the OnStar(R) Call Center first before pressing the emergency button in order to notify them of the test.
Ignition ON, press the OnStar(R) Call buttons one at the time. Verify that all of the OnStar(R) buttons operate normally.
If some OnStar(R) buttons are inoperative but not all, replace the inside rearview mirror.
If none of the OnStar(R) buttons operate, refer to circuit/system testing.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the 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 500k-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