B1020

DTC B1020

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



DTC Descriptor
DTC B1020 00
- Auxiliary Electronic Control Unit (ECU) 1 Performance




Circuit/System Description

The radio communicates with the Infotainment Faceplate Control Module or faceplate over the CAN Graphical Interface (CGI) serial data circuit. The CGI circuit is a UART - based serial data interface used to transfer messages and high rate display graphics.


When the faceplate is in the active state, the radio needs to determine if the faceplate is communicating properly. The radio initiates a Display Status Message to the faceplate and waits for a proper status response message back from the faceplate. If after 30 communication attempts without a proper response, the radio holds down the reset circuit in order to reset the faceplate.


This DTC indicates an internal ECU fault or a stuck button on the faceplate. No external circuits are involved.


Conditions for Running the DTC

* The ignition must be in the RUN or ACC position.
* The system voltage is at least 9.5 volts and no more than 15.5 volts.
* All the above conditions are present for greater than 10 seconds.



Conditions for Setting the DTC

The radio receives an improper status response message back from the faceplate. Just before the radio asserts the reset circuit, the DTC is set.


Conditions for Clearing the DTC

* A current DTC clears when the radio receives the proper status response message back from the faceplate.
* 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 Views)
Description and Operation

Radio/Audio System Description and Operation (Radio/Audio System Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information