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Radio information display, function disturbance - DTC U0257 (with monochrome display)

Radio information display, function disturbance - DTC U0257 (with monochrome display)

Diagnostic instruction


• Carry out Diagnostic system check - vehicle before carrying out this diagnostic procedure.

• See Strategy Based Diagnosis For an overview of the diagnostic procedure.

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


Circuit-/System description

The information display module is equipped with battery voltage and ground. Radio controls voltage status on the display via wake-up circuit. The display's background lighting strength and graphic data is communicated over the data circuit.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Component connector end view reference

Component Connector End Views

Description and Operation

Radio/Audio System Description and Operation


Electric information reference

• Circuit Testing

• Connector Repairs

• Testing for Intermittent Conditions and Poor Connections

• Wiring Repairs


Scan Tool References

Control Module References ** for information about diagnostic tools.

Circuit/System Verification

Ignition switch ON, radio ON, verify that the information display module switches on and that information is displayed on screen.

If the display does not switch on, go to Circuit/System Testing.

Circuit/System Testing


1. Ignition switch OFF, disconnect wiring harness connector P17 on information display module.

2. Check so that there are fewer than 10 Ω between the ground circuit pin 2 and ground.

3. If higher value, check if ground has open/has high resistance.

4. Check so that there are fewer than 20 Ω between the data circuit pin 6 and ground.

5. If higher value, check if ground has open/has high resistance. If the circuit tests OK, replace the A11 radio.

6. Check with a test lamp between B+ pin 1 and ground.

7. If the test lamp does not light, check if the B+-circuit has a short circuit to ground or an open/high resistance.

8. Ignition switch in DRIVE, check for 2-3 V between data circuit pin 7 and ground.

9. If the value is lower, check whether the data circuit is shorted to ground or is open/has high resistance. If the circuit tests OK, replace the A11 radio.

10. If higher value, check if the data circuit is short circuited to voltage. If the circuit tests OK, replace the A11 radio.

11. Ignition switch in DRIVE, check for 2-3 V between data circuit pin 8 and ground.

12. If the value is lower, check whether the data circuit is shorted to ground or is open/has high resistance. If the circuit tests OK, replace the A11 radio.

13. If higher value, check if the data circuit is short circuited to voltage. If the circuit tests OK, replace the A11 radio.

14. Check that there is less than 1 V between wake-up signal pin 4 and ground.

15. If higher value, check if the signal circuit is short circuited to voltage. If the circuit tests OK, replace the A11 radio.

16. Check that there is less than 1 V between reset pin 5 and ground.

17. If higher value, check if the signal circuit is short circuited to voltage. If the circuit tests OK, replace the A11 radio.

18. Ignition switch OFF, reconnect wiring harness connector P17 on information display module.

19. Disconnect wiring harness X1 connector from A11 radio.

20. Check that there is 4.5-5.5 V between signal circuit pin 27 and ground.

21. If the value is lower, check whether the signal circuit is shorted to ground or is open/has high resistance. If the circuit is OK, replace the P17 information display module.

22. If higher value, check if the signal circuit is short circuited to voltage. If the circuit is OK, replace the P17 information display module.

23. Check that there is 4.5-5.5 V between signal circuit pin 13 and ground.

24. If the value is lower, check whether the signal circuit is shorted to ground or is open/has high resistance. If the circuit is OK, replace the P17 information display module.

25. If higher value, check if the signal circuit is short circuited to voltage. If the circuit is OK, replace the P17 information display module.

26. If all circuits are normal, replace P17 information display module. Reconnect all wiring harness connectors.

27. Ignition switch DRIVE, radio ON, check that the information display module starts and that information is displayed on screen.

28. If the information display module still does not function, replace A11 radio.


Repair instructions

After completing the diagnostics procedure, carry out Diagnostic Repair Verification .


• Driver Information Display Replacement

• Control Module References for radio replacement, installation and programming.