For 1990-2009 cars only
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 Descriptor
DTC B1020 00: Auxiliary Electronic Control Unit (ECU) 1 PerformanceCircuit/System Description
The navigation radio communicates with the radio control assembly via serial data. If the radio receives an improper status response message, DTC B1020 will set.
This DTC indicates an internal ECU fault or a stuck button on the faceplate. No external circuits are involved.
Conditions for Running the DTC
| • | Ignition is ON or in the 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 indicating an internal ECU fault or a stuck button on the radio control assembly.
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. |
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
Verify that DTC B1020 is not set.
| ⇒ | If the DTC is set, replace the radio control assembly. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
