DTC Descriptor
DTC B1287: External Amp ControlDiagnostic Fault Information
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Remote Radio Control Signal | 2 | 2 | 1 | -- |
1. No audio output 2. Four Channel unmute, possible noise in speakers when radio muted or turned OFF. | ||||
Circuit/System Description
The radio provides a remote amp mute output circuit to control overall muting of remote non-GMLAN amplifiers with rear seat audio (RSA) applications. The amplifier receives pulse width modulation (PWM) signals on the circuit at varying duty cycle percentages for controlling the muted and unmuted functions of the amplifier. The RSA Enable circuit in the radio enables the rear seat channel muting 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.
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 retained accessory power (RAP) 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
The radio sets the DTC and continues normal operation.
Conditions for Clearing the DTC
| • | The condition must be corrected. |
| • | A history DTC clears after 100 malfunction-free ignition cycles. |
Reference Information
Schematic Reference
Connector End View Reference
Entertainment Connector End Views
Electrical Information Reference
Circuit/System Verification
Verify the audio system performance by adjusting the fade and balance of the speaker outputs.
Circuit/System Testing
- Ignition is OFF. Test the speaker output circuits between the amplifier and speakers for an open, a short to voltage or a short to ground.
- If the circuit tests normal, test or replace the amplifier.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
