OnStar® Button Assembly

WARNING: This page is about a different car, the 2007 Pontiac Montana SV6, 2007 Chevrolet Uplander, and 2007 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.

The OnStar® button assembly may be part of the rearview mirror on some vehicles or a separate unit on others. The button assembly is comprised of 3 buttons and a status LED. The buttons are defined as follows:

The answer/end call button, which is black with a white phone icon allows the user to answer and end calls or initiate the personal calling feature, if equipped.
The blue OnStar® call center button, which displays the OnStar® logo, allows the user to connect to the OnStar® call center.
The emergency button, which displays a white cross with a red background, sends a high priority emergency call to the OnStar® call center when pressed.

The OnStar® button assembly receives 10 volts on the keypad supply voltage circuit. When pressed, each button completes a circuit across a resister allowing a specific voltage to be returned to the vehicle communication interface module (VCIM) on the keypad signal circuit. Depending upon the voltage range returned, the VCIM is able to identify which button has been pressed.

The OnStar® status LED is located to the right of the emergency button on a mirror-mounted assembly and to the left of the answer/end call button when the assembly is mounted on the dash or overhead console. The LED is green when the system is ON and operating normally. When the status LED is green and flashing, it is an indication that a call is in progress. When the LED is red, this indicates a system malfunction is present. In the event there is a system malfunction and the OnStar® system is still able to make a call, the LED will flash red during the call. The OnStar® LED is controlled by the VCIM over the keypad red LED signal circuit and the keypad green LED signal circuit.