Pinpoint Test AY: DTC U0256 Or DTC U0255:00

Information and Entertainment System

Pinpoint Test AY: DTC U0256 Or DTC U0255:00

- DTC U0256 (Lost Communication With Front Display Interface Module)- set by the non-navigation Audio Control Module (ACM) when network messages are missing from the Front Display Interface Module (FDIM) for greater than 5 seconds with the ignition in RUN.

- DTC U0255:00 (Lost Communication With Front Display Interface Module: No Sub Type Information)- set by the APIM (Accessory Protocol Interface Module) when network messages are missing from the FDIM (Front Display Interface Module) for greater than 5 seconds with the ignition in RUN.

This pinpoint test is intended to diagnose the following:

- Communication network concern

- ACM (Audio Control Module)

- APIM (Accessory Protocol Interface Module)

- FDIM (Front Display Interface Module)

PINPOINT TEST AY : DTC U0256 OR DTC U0255:00

AY1 CHECK FOR LOST COMMUNICATION DTCs

NOTE: If new modules were installed prior to the DTC being set, the module configuration may be incorrectly set during Programmable Module Installation (PMI) or the PMI (Programmable Module Installation) may not have been carried out.

- Ignition ON.

- Clear continuous DTCs from all modules.

- Ignition OFF.

- Ignition ON.

- Wait at least 10 seconds.

- Retrieve all continuous DTCs from all modules.

Is DTC U0238 or DTC U0238:00 set in any audio system module?

Yes
GO to AY2.

No
The system is operating correctly at this time. The DTC may have been set due to an intermittent fault in the network wiring.

AY2 VERIFY THE CUSTOMER CONCERN

- Operate the audio system in radio tuner (AM/FM) mode.

Is an observable symptom present?

Yes
GO to AY3.

No
The system is operating correctly at this time. The DTC may have been set due to an intermittent fault in the network wiring. CHECK the MS-CAN (Medium Speed Controller Area Network) wiring between the FDIM (Front Display Interface Module) and the module in question for an intermittent fault.

AY3 CHECK THE COMMUNICATION NETWORK

- Carry out the network test using the scan tool.

Does the FDIM (Front Display Interface Module) pass the network test?

Yes
GO to AY4.

No
REFER to The FDIM (Front Display Interface Module) Does Not Respond To The Scan Tool in Information Bus.

AY4 CHECK FOR BATTERY VOLTAGE OUT-OF-RANGE DTCs

- Carry out the self-test for the following modules:
- ACM (Audio Control Module)

- APIM (Accessory Protocol Interface Module)

- FDIM (Front Display Interface Module)

Are any low or high voltage DTCs recorded in any module?

Yes
REFER to DTC Charts. Accessories and Optional Equipment

No
INSTALL a new FDIM (Front Display Interface Module). REFER to Front Display Interface Module (FDIM) . CLEAR the ACM (Audio Control Module) and APIM (Accessory Protocol Interface Module) DTCs. REPEAT the ACM (Audio Control Module) and APIM (Accessory Protocol Interface Module) self-tests.

If DTC U0256 is still present in the ACM (Audio Control Module), INSTALL a new ACM (Audio Control Module). REFER to Audio Control Module (ACM) . TEST the system for normal operation.

If DTC U0255:00 is still present in the APIM (Accessory Protocol Interface Module), INSTALL a new APIM (Accessory Protocol Interface Module).
REFER to Accessory Protocol Interface Module (APIM) . TEST the system for normal operation.