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. |
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.
Reference Information
Schematic Reference
Connector End View Reference
Entertainment/Communication Connector End Views
Description and Operation
OnStar Description and Operation
Electrical Information Reference
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the button assembly.
- Ignition ON, test for 9.8-10.2 volts between the keypad supply voltage circuit terminal A and ground.
- Test for 0 volt between the keypad signal circuit terminal B and ground.
- Test for 9.8-10.2 volts between the keypad supply voltage circuit terminal A and the keypad signal circuit terminal B.
- Test for less than 5 ohms between the ground circuit terminal E and ground.
- Ignition OFF, disconnect the CIM X1 connector. Test for infinite resistance between the keypad signal circuit terminal B and ground.
- If all circuits test normal, test or replace the button assembly.
| ⇒ | 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. |
| ⇒ | If greater than the specified range, test the keypad signal circuit for a short to voltage. If the circuit tests normal, replace the CIM. |
| ⇒ | If less than the specified range, test the keypad signal circuit for an open/high resistance. If the circuit tests normal, replace the CIM. |
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If less than the specified range, test the keypad signal circuit for a short to ground. |
Component Testing
- Ignition OFF, disconnect the harness connector at the button assembly.
- Test for infinite resistance between the keypad supply voltage terminal A and the keypad signal terminal B.
- 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.
- 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.
- 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.
| ⇒ | If less than the specified range, replace the button assembly. |
| ⇒ | If not within the specified range, replace the button assembly. |
| ⇒ | If not within the specified range, replace the button assembly. |
| ⇒ | If not within the specified range, replace the button assembly. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for CIM replacement, setup, and programming |
