Pinpoint Test AP: DTC U0255 Or DTC U0256:00

Information and Entertainment System

Pinpoint Tests

Pinpoint Test AP: DTC U0255 Or DTC U0256:00

Normal Operation
- 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 the RUN position.
- DTC U0256:00 (Lost Communication With Front Controls Interface Module: No Sub Type Information) - set by the navigation ACM or the Accessory Protocol Interface Module (APIM) when network messages are missing from the FCIM over the MS-CAN for greater than 5 seconds with the ignition in the RUN position.

This pinpoint test is intended to diagnose the following:

- Communication network concern
- ACM
- FCIM
- APIM


PINPOINT TEST AP: DTC U0255 OR DTC U0256:00

NOTE: Disregard the pinpoint test steps for the APIM if the concern is on a vehicle without the SYNC system.

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AP1 CHECK THE ACM AND APIM 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 may not have been carried out.

- Clear the ACM and APIM DTCs.
- Ignition OFF.
- Ignition ON.
- Wait at least 10 seconds.
- Repeat the ACM and APIM self-tests.
- Is DTC U0255 or DTC U0256:00 still present?

Yes
GO to AP2.

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

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AP2 VERIFY THE CUSTOMER CONCERN

- Ignition ON.
- Verify that there is an observable symptom present.
- Is an observable symptom present?

Yes
GO to AP3.

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 wiring between the FCIM and the module in question for an intermittent fault.

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AP3 CHECK THE COMMUNICATION NETWORK

- Ignition ON.
- Carry out the network test using the scan tool.
- Does the FCIM pass the network test?

Yes
GO to AP4.

No
REFER to Module Communications Network Testing and Inspection.

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AP4 CHECK FOR BATTERY VOLTAGE OUT-OF-RANGE DTCs

- Carry out the self-test for the following modules:
- ACM
- APIM
- FCIM
- Are any low or high voltage DTCs recorded in any module?

Yes
REFER to DTC Charts. Diagnostic Trouble Code Tests and Associated Procedures

No
INSTALL a new FCIM. REFER to Front Controls Interface Module (FCIM) Front Controls Interface Module (FCIM). CLEAR the ACM and APIM DTCs. REPEAT the ACM and APIM self-tests.

If DTC U0255 (without navigation) or DTC U0256:00 (with navigation) is still present in the ACM, INSTALL a new ACM. REFER to Audio Control Module (ACM) Audio Control Module (ACM). TEST the system for normal operation.

If DTC U0256:00 is still present in the APIM, INSTALL a new APIM. REFER to Accessory Protocol Interface Module (APIM) Accessory Protocol Interface Module (APIM). TEST the system for normal operation.

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