B1020

DTC B1020

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 Descriptor

DTC B1020 00
- Auxiliary Electronic Control Unit (ECU) Performance

Circuit/System Description

The radio communicates with the radio controls via serial data. This DTC indicates a fault in the radio controls. No external circuits are involved. The radio may continue to respond normally to faceplate functions when this DTC is set.

Conditions for Running the DTC

* Ignition is ON or in the ACC position.

* The system voltage is at least 9.5 V and no more than 15.5 V.

* All the above conditions are present for greater than 10 seconds.

Conditions for Setting the DTC

The radio receives an improper status response indicating an internal ECU fault in the radio controls.

Action Taken when the DTC Sets

No action is taken.

Conditions for Clearing the DTC

* A current DTC clears when the radio receives a proper status response message back from the radio control assembly.

* A history DTC clears after 50 malfunction-free ignition cycles.

Diagnostic Aids

* This DTC may be stored as a history DTC without affecting the operation of the radio controls.

* If stored only as a history DTC and not retrieved as a current DTC, do not replace the radio controls.

* If this DTC is retrieved as both a current and history DTC, replace the radio controls.

Reference Information

Schematic Reference

Radio/Navigation System Schematics Radio/Navigation System Schematics

Connector End View Reference

Component Connector End Views Fuel Pump and Level Sensor Assembly

Description and Operation

Radio/Audio System Description and Operation (with Monochrome Display) Radio/Audio System Description and Operation (with Monochrome Display)Radio/Audio System Description and Operation (with Color Display) Radio/Audio System Description and Operation (with Color Display)

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 Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.

2. Verify DTC B1020 is not set.

• If DTC B1020 is set
Replace the A20 radio/HVAC controls.

• If DTC B1020 is not set

3. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

Control Module References Control Module References for radio controls replacement, programming, and setup