Pinpoint Test AX: DTC U0255 Or DTC U0256:00

Information and Entertainment System

Pinpoint Test AX: DTC U0255 Or DTC U0256:00

- DTC U0255 (Lost Communication With Front Controls Interface Module)- set by the non-navigation Audio Control Module (ACM) when network messages are missing from the Front Controls Interface Module (FCIM) over the Medium Speed Controller Area Network (MS-CAN) for greater than 5 seconds with the ignition in RUN.

- DTC U0256:00 (Lost Communication With Front Controls Interface Module: No Sub Type Information)- set by the navigation ACM (Audio Control Module) or the Accessory Protocol Interface Module (APIM) when network messages are missing from the audio DSP (Digital Signal Processing) module over the MS-CAN (Medium Speed Controller Area Network) 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)

- FCIM (Front Controls Interface Module)

PINPOINT TEST AX : DTC U0255 OR DTC U0256:00

NOTE: Disregard the pinpoint test steps for the APIM (Accessory Protocol Interface Module) if the concern is on a vehicle without the SYNC(R) system.

AX1 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 the ACM (Audio Control Module) and APIM (Accessory Protocol Interface Module) DTCs.

- Ignition OFF.

- Ignition ON.

- Wait at least 10 seconds.

- Repeat the ACM (Audio Control Module) and APIM (Accessory Protocol Interface Module) self-test.

Is DTC U0255 or DTC U0256:00 still present?

Yes
GO to AX2.

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

AX2 VERIFY THE CUSTOMER CONCERN

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

- Verify there is an observable symptom present.

Is an observable symptom present?

Yes
GO to AX3.

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 FCIM (Front Controls Interface Module) and the module in question for an intermittent fault.

AX3 CHECK THE COMMUNICATION NETWORK

- Carry out the network test using the scan tool.

Does the FCIM (Front Controls Interface Module) pass the network test?

Yes
GO to AX4.

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

AX4 CHECK FOR BATTERY VOLTAGE OUT-OF-RANGE DTCs

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

- Audio DSP (Digital Signal Processing) 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 FCIM (Front Controls Interface Module). REFER to Front Controls Interface Module (FCIM) . 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 U0255 or U0256:00 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 U0256:00 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.