Radio controls, function interference (with monochrome display)

/ 9-4x / 2011 / 3. Electrical System / Audio system with navigation / Fault diagnosis, fault symptoms / Radio controls, function interference (with monochrome display)

Diagnostic Instructions

1.	Carry out Diagnostic system check - Vehicle before you use this diagnostic procedure.

2.	See Strategy Based Diagnosis for an overview of the diagnostic approach.

3.	Instructions for diagnosis procedure gives an overview of each diagnostic category.

Circuit-/System description

The radio/HVAC controls are powered by the battery and ground. The radio/HVAC controls control the radio functions via the serial data messages. The radio-/ HVAC controls communicate requests to the info display module with LIN serial data. The Info Display module communicates these requests to the radio via CGI serial data.

Communication between HVAC controls and the HVAC module is via a separate LIN circuit. The HVAC control module communicates the status information to the radio via GMLAN for HVAC information display.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Contact end displays the reference

Component Connector End Views

Description and use

Radio/Audio System Description and Operation

Electric reference information

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

Control module, references for information about the diagnostic tool.

Circuit/System Verification

1.	Check that no DTCs have been recently set.

2.	If a DTC has been set that is relevant, see Diagnostic trouble code (DTC) list - vehicle .

3.	Ignition ON, radio ON, check that the radio/HVAC has background lighting and functions correctly.

4.	If some, but not all controls function normally, replace the radio/HVAC controls.

5.	If no controls function, see Circuit- / System Test.

Circuit/System test

1.	Ignition OFF, disconnect the cable harness at A20 radio/HVAC controls.

2.	Test for less than 10 Ω between the ground circuit terminal 17 and ground.

3.	If greater than stated range, test the ground circuit for open/high resistance.

4.	Verify that a test lamp illuminates between the B+ circuit terminal 10 and ground

5.	If the test lamp does not illuminate, test the B+ circuit for a short to ground or open/high resistance.

6.	Ignition ON, test for 2-11.5 V between the data circuit terminal 7 and ground.

7.	If less than the stated range, check the data circuit for short circuit to ground or open/high resistance. If the circuit functions normally, replace the P17 module info display.

8.	If greater than stated range, test the data circuit for short circuit to voltage. If the circuit functions normally, replace the P17 module info display.

9.	If all circuits function normally, replace the A20 radio/HVAC controls.

Repair Instructions

Carry out Confirmation of diagnostic repair after completing the repair.

•	Driver Information Display Replacement

•	Control module, references for radio control module, installation, replacement, installation and programming.

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