B1287

DTC B1287

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions 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 remote amplifier mute output circuit to control overall muting of remote amplifiers (U65). The amplifier receives pulse width modulated (PWM) signals on the control circuit at varying duty cycle percentages for controlling muted and unmuted functions of the amplifier. Circuitry internal to the radio monitors the remote amplifier mute circuit for faults and sets the appropriate DTC when faults are detected.

Conditions for Running the DTC

* The ignition is ON.
* Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

The DTC will set when the radio detects a short to voltage, short to ground, or an open/high resistance in the amplifier control circuit 400 ms after the radio activates the remote enable circuit.

Action Taken When the DTC Sets

The 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 condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

A short to ground may cause noise in the speakers when the radio is muted or turned OFF.

Circuit/System Testing

1. Ignition OFF, disconnect the X3 harness connector at the audio amplifier.
2. Ignition ON, radio ON, test for 0.6-1.0 volts between the control circuit terminal 16 and ground.

^ If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the radio.

^ If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.

3. If all circuits test normal, replace the audio amplifier.

Repair Instructions

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

* Radio Speaker Amplifier Replacement