GM Service Manual Online
For 1990-2009 cars only

DTC Descriptor

DTC 1287: External Amp Control

Diagnostic 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

Amp Control

DTC B1287

DTC B1287

DTC B1287¹

--

¹ No audio output.

Circuit/System Description

The amplifier receives PWM signals on the circuit at varying duty cycle percentages for controlling the muted and unmuted functions of 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

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

Radio/Audio System Schematics

Connector End View Reference

Entertainment Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Circuit/System Verification

Verify the audio system performance by adjusting the fade and balance of the speaker outputs.

Circuit/System Testing

Ignition OFF, test the remote radio control signal circuit for an open, a short to voltage, or a short to ground. If the circuit tests normal, replace the radio.

If the circuit tests normal, replace the radio.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Radio Speaker Amplifier Replacement