Pinpoint Test I : U0121:00

WARNING: This page is about a different car, the 2018 Ford F-550 Super Duty, 2018 Ford F-450 Super Duty, 2018 Ford F-350 Super Duty, and 2018 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.

I1 CHECK THE COMMUNICATION NETWORK
- Ignition ON.
- Using a diagnostic scan tool, carry out the Network Test.
Does the ABS module pass the Network Test?

Yes GO to I2

No DIAGNOSE the ABS module does not communicate with the diagnostic scan tool. REFER to: Communications Network .

I2 CHECK THE TBM (TRAILER BRAKE CONTROL MODULE) CONTINUOUS MEMORY DIAGNOSTIC TROUBLE CODES (CMDTCS)

Using a diagnostic scan tool, carry out the TBM self-test.

Clear the TBM Diagnostic Trouble Codes (DTCs).

Ignition OFF.

Ignition ON.

Wait at least 10 seconds for all modules to wake up and prove out.

Using a diagnostic scan tool, carry out the TBM self-test.

Record the TBM Diagnostic Trouble Codes (DTCs).

Is DTC U0121:00 retrieved again?

Yes

GO to I3

No	The system is operating correctly at this time. The DTC may have been set due to high network traffic or an intermittent fault condition.

I3 REVIEW THE RECORDED DIAGNOSTIC TROUBLE CODES (DTCS) FROM THE TBM (TRAILER BRAKE CONTROL MODULE) SELF-TEST
- Review the recorded Diagnostic Trouble Codes (DTCs) from the TBM self-test.
Is DTC U3003:16 or U3003:17 present in the TBM?

Yes For DTC U3003:16, GO to Pinpoint Test F For DTC U3003:17, GO to Pinpoint Test E

No GO to I4

I4 RETRIEVE THE DIAGNOSTIC TROUBLE CODES (DTCS) FROM THE ABS (ANTI-LOCK BRAKE SYSTEM) MODULE SELF-TEST
- Using a diagnostic scan tool, carry out the ABS module self-test.
Is DTC U3003:16 or U3003:17 present in the ABS module?

Yes DIAGNOSE the ABS module Diagnostic Trouble Codes (DTCs). REFER to: Anti-Lock Brake System (ABS) and Stability Control .

No GO to I5

I5 CHECK FOR OTHER CAUSES OF COMMUNICATION NETWORK CONCERN

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

Check the vehicle service history for recent service actions related to the ABS module or TBM. If recent service history is found:
- verify the correct replacement module was installed.
  - HVBOM may be used to verify correct part fitment.
- verify the configuration of replacement module was correct.
  - re-configure the module using as-built data if prior configuration is suspect.
- verify the module was not obtained from a like vehicle and installed into customer vehicle.
  - return the swapped module to source vehicle and obtain new replacement module.

Operate the system and determine if the observable symptom is still present.

Is the observable symptom still present?

Yes

GO to I6

No	The system is operating correctly at this time. The concern may have been due to incorrect parts replacement procedures or incorrect module configuration.

I6 CHECK FOR DTC (DIAGNOSTIC TROUBLE CODE) U0121:XX SET IN OTHER MODULES

Using a diagnostic scan tool, carry out the self-test for all modules.

Retrieve the Continuous Memory Diagnostic Trouble Codes (CMDTCs) from all modules.

Is DTC U0121:xx set in 1 or more modules in addition to the TBM?

Yes	CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW the TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new ABS module. REFER to: Anti-Lock Brake System (ABS) Module .

No	CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW the TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new TBM. REFER to: Trailer Brake Control Module (TBM) .