B2476

DTC B2476

CIRCUIT DESCRIPTION
The OnStar(R) button assembly consists of three buttons, Call/Answer, OnStar(R) Call Center and OnStar(R) Emergency. Ten volts is supplied to the button assembly on the keypad supply voltage circuit-Each of the buttons, when pressed, completes the 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.

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 ms.

CONDITIONS FOR SETTING THE DTC
- The keypad signal circuit voltage to the VCIM is less than 2.8 volts or more than 3.2 volts.
- The above conditions are present for greater than 300 ms.

ACTION TAKEN WHEN THE DTC SETS
- The VCIM will ignore all inputs from the OnStar(R) button assembly.
- No calls can be placed.
- The OnStar(R) status LED turns RED.

CONDITIONS FOR CLEARING THE DTC
- The keypad signal circuit voltage is between 2.8 volts and 3.2 volts.
- A history DTC clears after 50 malfunction free ignition cycles.
- The VCIM receives the clear DTC command from the scan tool.

TEST DESCRIPTION

Steps 1-6:

Steps 7-11:

The number below refers to the step number on the diagnostic table.
2. This step checks that the VCIM is sending out the proper supply voltage.