B1287

DTC B1287

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 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 amplifier control circuit provides varying pulse width modulated (PWM) signals to control overall muting of the amplifier. The PWM signals are varying duty cycle percentages ranging from 0-100 percent. A low duty cycle unmutes all amplifier channels and a high duty cycle mutes all amplifier channels. The radio monitors the amp control circuit for faults.

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 V and no more than 16 V.

Conditions for Setting the DTC

The radio detects a fault on the amplifier control circuit 400 ms after radio activates the remote enable circuit.

Action Taken When the DTC Sets

Radio sets the DTC and continues to output correct state.

Conditions for Clearing the DTC

* The condition must be corrected.
* A history DTC clears after 100 malfunction-free ignition cycles.
* The radio receives the clear code command from the scan tool.

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 Verification

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

Circuit/System Testing

1. Ignition OFF, disconnect the X1 harness connector at the A11 radio.
2. Ignition ON, test for less than 1 V between the radio audio mute signal terminal 37 and ground.

• If greater than the specified value, test the circuit for a short to voltage. If the circuit tests normal, replace the T3 amplifier.

3. Ignition OFF, test for greater than 20 Ohms between the radio audio mute signal terminal 37 and ground.

• If less than the specified value, test the circuit for a short to ground. If the circuit tests normal, replace the T3 amplifier.

4. Ignition OFF, disconnect the X3 harness connector at the T3 amplifier.
5. Test for less than 5 Ohms between the radio X1 terminal 37 and the amplifier X1 terminal 7.

• If greater than specified range, test the circuit for an open/high resistance.

6. If all circuits test normal, replace the A11 radio.

Repair Instructions

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

Control Module References (Programming and Relearning)for radio and amplifier replacement, setup, and programming