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 BatteryDTC 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 |
|---|---|---|---|---|
Amplifier Control Signal Circuit | B1287 02 | B1287 04 | B1287 01 | -- |
Circuit/System Description
The radio provides a radio audio mute signal circuit to control overall muting of remote non-serial data amplifiers. The amplifier receives PWM signals on the circuit at varying duty cycle percentages for controlling the muted and unmuted functions of the amplifier. A diagnostic sense circuit internal to the radio monitors the remote amp mute circuit for faults and sets the appropriate DTC when detected. The radio outputs a low duty cycle signal to produce an unmuted condition at the amplifier. The radio outputs a high duty cycle signal to produce a muted condition at 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
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
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 short or open condition must be corrected. |
| • | A history DTC clears after 100 malfunction- free ignition cycles. |
Diagnostic Aids
A short to ground may cause a buzz in the speakers when the radio is muted or turned OFF.
Reference Information
Schematic Reference
Radio/Navigation System Schematics
Connector End View Reference
Description and Operation
Radio/Audio System Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Turn the radio on. Adjust the fade and balance control to test for audio sound from each individual channel.
Circuit/System Testing
- Ignition OFF, disconnect the X3 harness connector at the amplifier.
- Ignition ON, radio ON, test for 0.6-1.0 volts at the radio audio mute signal X3 terminal 6 and ground.
- Press the phone mute button on the steering wheel control switch. Test for 6.0-8.0 volts at the radio audio mute signal X3 terminal 6 and ground .
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio. |
| ⇒ | If less than the specified range, test the signal circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the radio. |
| ⇒ | If not within the specified range, replace the radio. |
| ⇒ | If all circuits test normal, replace the amplifier. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for radio or amplifier replacement, setup, and programming.
