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Home >> Buick >> 2013 >> Verano L4-2.0L Turbo >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> B Code Charts >> B1278

B1278




DTC B1278 or B1279

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B1278 01
- Left Auxiliary Input Signal Circuit Short to Battery

DTC B1278 02
- Left Auxiliary Input Signal Circuit Short to Ground

DTC B1279 01
- Right Auxiliary Input Signal Circuit Short to Battery

DTC B1279 02
- Right Auxiliary Input Signal Circuit Short to Ground

Diagnostic Fault Information






Circuit/System Description

A remote 3.5 mm auxiliary stereo jack allows playback of audio signals from remote devices (e.g., laptop computer, IPOD, MP3 player, etc.). The auxiliary audio jack has an internal mechanical detection switch. The switch is normally closed, connecting the detection circuit to the audio common circuit. When a device is inserted to the auxiliary audio jack, the switch opens and the multimedia player interface module detects a high voltage on the detection circuit. A serial data message is sent to the radio, the radio will switch to AUX as the audio source. The multimedia player interface module receives the analog audio signals from the connected device and sends the signals to the radio.

Conditions for Running the DTC

* Ignition in RUN or ACC position.

* The system voltage is at least 9.5 V and no more than 15.5 V.

* The multimedia player interface module detects a device has been connected to the auxiliary audio input jack.

Conditions for Setting the DTC

B1278 01, B1279 01

* The multimedia player interface module detects a short to battery on either of the audio signal circuits from the auxiliary audio jack.

* The condition is present for greater than 250 mS.

B1278 02, B1279 02

* The multimedia player interface module detects a short to ground on either of the audio signal circuits from the auxiliary audio jack.

* The condition is present for greater than 250 mS.

Action Taken When the DTC Sets

No or reduced audio is heard from the remote audio device.

Conditions for Clearing the DTC

* The conditions for setting the DTC are no longer present on the auxiliary input signal circuits.

* A history DTC clears after 50 malfunction-free ignition cycles.

Diagnostic Aids

* Playback of an audio device that is connected to the 3.5 mm jack can only be controlled using the controls on the device.

* The volume control on the device may need to be adjusted to ensure sufficient playback volume through the infotainment system.

* This DTC may be stored as a history DTC without affecting the operation of the module.

* If stored only as a history DTC and not retrieved as a current DTC, do not replace the module.

Reference Information

Schematic Reference

Radio/Navigation System Schematics Radio/Navigation System Schematics

Connector End View Reference

Component Connector End Views Outside Rearview Mirror - Driver

Description and Operation

Radio/Audio System Description and Operation (with Color Display) Radio/Audio System Description and Operation (with Color Display)Radio/Audio System Description and Operation (with Monochrome Display) Radio/Audio System Description and Operation (with Monochrome Display)

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

Auxiliary Audio Input Jack

1. Ignition ON, radio ON.

2. Verify the infotainment system switches to AUX as the audio source with a portable audio playback device connected to the auxiliary audio input jack.

• If the infotainment system does not switch to AUX as the audio source
Refer to Auxiliary Audio Input Malfunction Auxiliary Audio Input Malfunction.

• If the infotainment system switches to AUX as the audio source

3. Verify DTC B1278 or DTC B1279 is not set.

• If DTC B1278 or DTC B1279 is set
Refer to Circuit/System Testing.

• If DTC B1278 or DTC B1279 is not set

4. Verify the audio from the device is heard through the vehicle infotainment system while operating the device to begin audio playback, adjusting the volume on the device if necessary.

• If audio is not heard from the device

1. Connect a different device to the auxiliary audio jack.

2. Verify the audio from the device is heard through the vehicle infotainment system while operating the device to begin audio playback, adjusting the volume on the device if necessary.

• If audio cannot be heard from any device connected to the auxiliary audio input jack, refer to Auxiliary Audio Input Malfunction Auxiliary Audio Input Malfunction.

• If audio can be heard from device.

3. The malfunction is related to the external device connected to the input.

• If audio is heard from the device

5. All OK

Circuit/System Testing

1. Ignition OFF, disconnect the X1 harness connector at the X83 auxiliary audio input. Ignition ON, radio ON.

2. Test for less than 1 V between the signal circuits listed below and ground:

* left auxiliary audio signal circuit terminal 1

* right auxiliary audio signal circuit terminal 2

* auxiliary audio common signal circuit terminal 3

• If 1 V greater

1. Ignition OFF, disconnect the harness connector at the T11 multimedia player interface module. Ignition ON.

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 T11 multimedia player interface module.

• If less than 1 V

3. Ignition OFF, disconnect the harness connector at the T11 multimedia player interface module.

4. Test for infinite resistance between the signal circuits listed below and ground:

* auxiliary audio common signal circuit terminal 3

* left auxiliary audio signal circuit terminal 12

* right auxiliary audio signal circuit terminal 13

• If less than infinite resistance
Repair the short to ground on the circuit.

• If infinite resistance

5. Test for less than 5 ohms between the signal circuit terminals listed below:

* T11 multimedia player interface module X1 terminal 3 and the X83 auxiliary audio input X1 terminal 3

* T11 multimedia player interface module X1 terminal 12 and the X83 auxiliary audio input X1 terminal 1

* T11 multimedia player interface module X1 terminal 13 and the X83 auxiliary audio input X1 terminal 2

• If 5 ohms greater
Repair the open/high resistance in the circuit.

• If less than 5 ohms

6. Replace the X83 auxiliary audio input. Connect all harness connectors.

7. Connect and operate the portable audio playback device.

8. Verify DTC B1278 or DTC B1279 is not set.

• If DTC B1278 or DTC B1279 is set
Replace the T11 multimedia player interface module.

• If DTC B1278 or DTC B1279 is not set

9. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* Audio Disc Player and USB Receptacle Replacement Audio Disc Player and USB Receptacle Replacement

* Control Module References Control Module References for multimedia player interface module replacement, programming, and setup.

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