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.). When a remote device audio mini-plug is inserted in the remote auxiliary jack, an internal mechanical switch closes completing the aux jack detect circuit to the radio. The radio automatically detects the input through the circuit and the device begins playing. The radio receives the devices audio signals on the auxiliary input 1 (left) signal circuit and auxiliary input 2 (right) signal circuit. If equipped with a multimedia player interface module, the auxiliary inputs that would normally connect directly to the radio will have the multimedia player interface module inline of those connections. This means that the auxiliary inputs for the radio connect to the multimedia player interface module, and the multimedia player interface module connects to the radio, passing along the audio signals. Only the multimedia player interface module can set these DTCs.
The auxiliary audio jack has an internal mechanical detection switch that will connect the detection signal on the auxiliary audio jack to ground when an auxiliary mini-plug is inserted.
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.
Conditions for Setting the DTC
* The multimedia player interface module detects a short to battery on the signal circuit terminal 1 or signal circuit terminal 2.
* The multimedia player interface module detects a short to ground on the signal circuit terminal 1 or signal circuit terminal 2.
* All the above conditions are present for greater than 250 mS.
Action Taken When the DTC Sets
No 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
* 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 (Connector End Views By Name)
Description and Operation
Radio/Audio System Description and Operation (Radio/Audio System)
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 (Programming and Relearning) 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:
* 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.
3. Ignition OFF, test for infinite resistance between the terminals listed below and ground:
* 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.
4. If all of the circuits test normal, replace the auxiliary audio jack.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
Control Module References (Programming and Relearning) multimedia player interface module replacement, setup, and programming