For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | 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 | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Radio Mute Signal | DTC B1287 02 | DTC B1287 04 | DTC B1287 01 | --

### Circuit/System Description

The radio provides a remote amplifier mute output circuit to control overall muting of the remote amplifier. 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 following are conditions that must be present in order for the radio to enable the diagnostics.

• | Radio ON

• | The system voltage is at between 9 - 16 V

### Conditions for Setting the DTC

A short to voltage, short to ground, or an open is seen on 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

• | A current DTC clears when the condition for setting the DTC is no longer present

• | A history DTC clears after 100 malfunction- free ignition cycles

### Reference Information

#### Schematic Reference

Radio/Navigation System Schematics

#### Connector End View Reference

Entertainment/Communication Connector End Views

#### Description and Operation

Radio/Audio System Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Verification

Radio ON, adjust the fade and balance control to verify audio is present at each individual channel.

### Circuit/System Testing

1. Ignition OFF, disconnect the C3 harness connector at the audio amplifier.
2. Radio ON, test for test for 0.5 - 1.0 V between the terminal 11 ground.

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

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. 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.

Control Module References for Radio and Amplifier replacement, setup, and programming