B1287

DTC B1287

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



DTC Descriptors
DTC B1287 01
- Amplifier Control Signal Circuit Short to Battery

DTC B1287 02
- Amplifier Control Signal Circuit Short to Ground

DTC B1287 04
- Amplifier Control Signal Circuit Open




Diagnostic Fault Information






Circuit/System Description

The radio provides a radio audio mute signal circuit to control overall muting of remote non-GMLAN amplifiers. The amplifier receives PWM signals on the circuit at varying duty cycle percentages for controlling the muted and unmuted functions of the amplifier. A diagnostic sense circuit internal to the radio monitors the remote amp mute circuit for faults and sets the appropriate DTC when detected. The radio outputs a low duty cycle signal to produce an unmuted condition at the amplifier. The radio outputs a high duty cycle signal to produce a muted condition at the amplifier.


Conditions for Running the DTC

The following are conditions that must be present in order for the radio to enable the diagnostics.

* The radio is in ACCESSORY, RUN, or RAP power mode.
* The system voltage is at least 9 volts and no more than 16 volts.



Conditions for Setting the DTC

Circuit failure 400 ms after radio activates remote enable.


Action Taken When the DTC Sets

Radio sets the DTC and continues to output the correct muted or unmuted amplifier state based on the fault condition on the circuit.


Conditions for Clearing the DTC

* The short or open condition must be corrected.
* A history DTC clears after 100 malfunction- free ignition cycles.



Diagnostic Aids

If DTC B1287 is current and the circuit is shorted to ground, there may be possible noise in the speakers when the radio is muted or turned off.


Reference Information
Schematic Reference

Radio/Navigation System Schematics (Radio/Navigation System Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Radio/Audio System Description and Operation (Radio/Audio System Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Programming and Relearning (Programming and Relearning) for scan tool information


Circuit/System Verification

Turn the radio on. Adjust the fade and balance control to test for audio sound from each individual channel.


Circuit/System Testing

1. Ignition OFF, disconnect the X3 harness connector at the amplifier.
2. Ignition ON, radio ON, test for 0.6-1.0 volts at the radio audio mute signal X3 terminal 7 and ground.

• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.
• If less than the specified range, test the signal circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the radio.

3. Press the phone mute button on the steering wheel control switch. Test for 6.0-8.0 volts at the radio audio mute signal X3 terminal 7 and ground .

• If not within the specified range, replace the radio.
• If all circuits test normal, replace the amplifier.




Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.


Programming and Relearning (Programming and Relearning) for radio or amplifier replacement