U1306

DTC U1306

CIRCUIT DESCRIPTION
This vehicle utilizes both a Class 2 and Entertainment and Comfort Serial Data line for communication with the OnStar(R) Vehicle Communication Interface Module (VCIM). Class 2 messaging is utilized for inter-module information transfer to support features such as remote door locking and unlocking. Because this vehicle does not utilize a Class 2 supported radio, the E & C data line must be implemented to transfer the OnStar(R) audio signals from the VCIM to the vehicle audio system. In the event the Entertainment and Comfort Serial Data line is shorted to ground, shorted to voltage or opened, U1306 is set as current and can be read through the use of the scan tool over the Class 2 Serial Data line. Calls will still be placed to the OnStar(R) Call Center if a keypress is make, however, no OnStar(R) audio will be heard and the radio will not mute if currently turned on.

CONDITIONS FOR RUNNING THE DTC
- The ignition must be in the RUN or ACC position, or retained accessory power (RAP) must be active.
- The system voltage is at least 9.5 volts and no more than 15.5 volts.
- All of the above conditions are present for greater than 300 ms.

ACTION TAKEN WHEN THE DTC SETS
- The VCIM does not communicate with the radio.
- No OnStar(R) audio is heard and the radio will not mute after a keypress is made.
- The OnStar(R) status LED turns Red.

CONDITIONS FOR CLEARING THE MIL/DTC
- The VCIM does not detect a short to ground on the Entertainment and Comfort Serial Data Bus
- The VCIM does not detect a short to voltage on the Entertainment and Comfort Serial Data Bus
- The VCIM does not detect an open in the Entertainment and Comfort Serial Data Bus
- A history DTC clears after 50 malfunction free ignitions cycles
- The VCIM detects the clear DTC command from the scan tool

TEST

Steps 1 - 2:

Steps 3 - 9: