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DTC B1278 or B1279

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 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

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

B+

--

4

--

--

Detection Signal Circuit

4

5

5

--

Left Audio Signal Terminal 12

B1278 02, 3

3

B1278 01, 3

--

Left Audio Signal Terminal 14

3

3

3

--

Right Audio Signal Terminal 13

B1279 02, 2

2

B1279 01, 2

--

Right Audio Signal Terminal 15

2

2

2

--

Audio Common Circuit

--

1

--

--

Ground

--

4

--

--

1. No or distorted audio from both sides

2. No or distorted right side audio

3. No or distorted left side audio

4. External audio inputs inoperative

5. AUX selection always available with or without device connected

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 analogue 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

Connector End View Reference

Component Connector End Views

Description and Operation

Radio/Audio System 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 OFF, disconnect the X1 harness connector at the auxiliary audio jack.
  2. Ignition ON, test for less than 1 V between the terminals listed below and ground:
  3. • Signal terminal 1
    • Signal terminal 2
    If greater than the specified value, test the circuit for a short to voltage. If the circuit tests normal, replace the multimedia player interface module.
  4. Ignition OFF, test for infinite resistance between the terminals listed below and ground:
  5. • Signal terminal 1
    • Signal terminal 2
    If less than the specified value, test the circuit for a short to ground. If the circuit tests normal, replace the multimedia player interface module.
  6. If all of the circuits test normal, replace the auxiliary audio jack.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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

   


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