Pinpoint Test AF: DTC U0255 Or DTC U0256:00
Information and Entertainment System
Pinpoint Tests
Pinpoint Test AF: DTC U0255 Or DTC U0256:00
- DTC U0255 (Lost Communication With Front Controls Interface Module) - set by the 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 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 RUN.
This pinpoint test is intended to diagnose the following:
- Communication network concern
- ACM
- APIM
- FCIM
PINPOINT TEST AF: 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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AF1 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 may not have been carried out.
- Ignition ON.
- Clear the ACM and APIM DTCs.
- Ignition OFF.
- Ignition ON.
- Wait at least 10 seconds.
- Repeat the ACM and APIM self-test.
- Is DTC U0255 or DTC U0256:00 still present?
Yes
GO to AF2.
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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AF2 VERIFY THE CUSTOMER CONCERN
- Operate the audio system in various modes (radio tuner, SYNC, etc.).
- Verify there is an observable symptom present.
- Is an observable symptom present?
Yes
GO to AF3.
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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AF3 CHECK THE COMMUNICATION NETWORK
- Carry out the network test using the scan tool.
- Does the FCIM pass the network test?
Yes
GO to AF4.
No
REFER to The FCIM Does Not Respond To The Scan Tool in Module Communications Network Testing and Inspection.
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AF4 CHECK FOR BATTERY VOLTAGE OUT-OF-RANGE DTCs
- Carry out the self-test for the following modules:
- ACM
- Audio DSP module
- FDIM
- Are any low or high voltage DTCs recorded in any module?
Yes
REFER to DTC Charts. [1][2]Diagnostic Trouble Code Descriptions
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 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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