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 amplifier control circuit will measure less than 1 V when the mute function is OFF, and approximately 8 V DC when at full mute. 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 no longer be present.
* A history DTC clears after 50 malfunction-free ignition cycles.

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

Ignition ON, radio ON, verify that the radio mute button functions are working properly.

If the radio mute button is inoperative, refer to Circuit/System Testing.

Circuit/System Testing

1. Ignition OFF, disconnect the X3 harness connector at the T3 amplifier.
2. Ignition ON, radio ON, mute OFF, test for less than 1 V between the amplifier control circuit terminal 11 and ground.

• If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the A11 radio.

3. Mute ON, test for 7.5-8.5 V between the amplifier control circuit terminal 11 and ground.

• 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 A11 radio.
• If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the A11 radio.

4. If all circuits test normal, replace the T3 amplifier.

Repair Instructions

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

Control Module References (Programming and Relearning) for A11 radio and T3 amplifier replacement, setup, and programming