DTC B15A0

Cellular, Entertainment, and Navigation | Diagnostic Information and Procedures | Document ID: 5201056 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. DTC Descriptors DTC B15A0 Telematics Speaker (-) For symptom byte information refer to Symptom Byte List. Diagnostic Fault Information

Circuit number	Circuit Function	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performan
4769	Control	B15A0 14	B15A0 14	—	—

Circuit/System Description The Telematics Control Module utilizes the vehicles infotainment systems speaker to broadcast audio in the case of emergency road assistance. In the event the infotainment system becomes inoperable there is an emergency backup speaker connected directly to the Telematics Control Module. Each of the audio output channel circuits (+) and (-), at the Telematics Control Module have a DC bias voltage that is approximately one half of battery voltage. When using a DMM, each of the audio output channel circuits will measure approximately 6.5 V DC. The audio being played on the system is produced by a varying AC voltage that is centered around the DC bias voltage on the same circuit. The AC voltage is what causes the speaker cone to move and produce sound. The frequency (Hz) of the AC voltage signal is directly related to the frequency of the input. Both the DC bias voltage and the AC voltage signals are needed for the system to properly produce sound. Conditions for Running the DTC Ignition is ON or in the ACC position The system voltage is 9-16 V The test is run once every 10 s Conditions for Setting the DTC B15A0 11 The Telematics Control Module detects a short to ground on the audio signal (-) circuit. B15A0 13 The Telematics Control Module detects an open on the audio signal (-) circuit. Action Taken When the DTC Sets The red LED status indicator is illuminated. Conditions for Clearing the DTC Conditions for Clearing the DTC A current DTC clears when the conditions for setting the DTC are no longer present and the ignition has been cycled from OFF to ON. A history DTC clears after 40 malfunction-free ignition cycles. Reference Information Schematic Reference OnStar/Telematics Schematics Connector End View Reference Master Electrical Component List Description and Operation OnStar Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Scan Tool Reference Control Module References for scan tool information Circuit/System Testing

1. Ignition/Vehicle Off and all vehicle systems Off, disconnect the harness connector at the P50 Emergency/Call Backup Speaker . Ignition ON/Vehicle in Service Mode.
2. Test for 5–7 V between each audio signal circuit terminal 1 and ground. ⇒ If less than 5 V 2.1. Ignition OFF, disconnect the harness connector X1 at the K73 Telematics Control Module. 2.2. Test for infinite resistance between the signal circuit and ground. ⇒ If less than infinite resistance, repair the short to ground on the circuit. ⇓ If infinite resistance 2.3. Test for less than 2 Ω in the signal circuit end to end. ⇒ If 2 Ω or greater, repair the open/high resistance in the circuit. ⇒ If less than 2 Ω, replace the K73 Telematics Control Module. ⇒ If greater than 7 V 2.1. Ignition OFF, disconnect the harness connector X1 at the K73 Telematics Control Module. Ignition ON/Vehicle in Service Mode. 2.2. Test for less than 1 V between the signal circuit and ground. ⇒ If 1 V or greater, repair the short to voltage on the circuit. ⇒ If less than 1 V, replace the K73 Telematics Control Module. ⇓ If between 5–7 V
3. Test or replace the P50 Emergency/Call Backup Speaker. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Control Module References for radio replacement, programming, and setup.