Pinpoint Test A : U0121
WARNING: This page is about a different car, the 2016 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
- A1 VERIFY THE CUSTOMER CONCERN
- Ignition ON.
- Verify there is an observable symptom present.
Is an observable symptom present?
Yes GO to A2. No The system is operating normally at this time. The may have been set due to high network traffic or an intermittent fault condition. - A2 CHECK THE COMMUNICATION NETWORK
- Using a diagnostic scan tool, perform a network test.
Does the ABS module pass the network test?
Yes GO to A3. No REFER to Module Communications Network . - A3 PERFORM ABS MODULE SELF-TEST
- Using a diagnostic scan tool, perform a ABS module self-test.
Are any Diagnostic Trouble Codes (DTCs) recorded?
Yes REFER to Anti-Lock Brake System (ABS) and Stability Control . No GO to A4. - A4 CHECK THE Diagnostic Trouble Codes (DTCs)
- Using a diagnostic scan tool, retrieve the Diagnostic Trouble Codes (DTCs).
Are any Diagnostic Trouble Codes (DTCs) recorded?
Yes REFER to Multifunction Electronic Modules . No GO to A5. - A5 PERFORM THE SELF-TEST
- Using a diagnostic scan tool, perform the self-test.
Is P0562 or P0563 recorded?
Yes REFER to PCM DTC Chart . No GO to A6. - A6 RECHECK THE PCM DIAGNOSTIC TROUBLE CODES (DTCs)NOTE: If new modules were installed prior to the DTC being set, the module configuration may be incorrectly set during the PMI, or the PMI may not have been carried out.
- Using a diagnostic scan tool, clear the Diagnostic Trouble Codes (DTCs).
- Wait 10 seconds.
- Repeat the PCM self-test.
Is PCM U0121 still present?
Yes GO to A7. 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. - A7 CHECK FOR DTC U0121 SET IN OTHER MODULES
- Using a diagnostic scan tool, clear all Diagnostic Trouble Codes (DTCs).
- Ignition OFF.
- Ignition ON.
- Wait 10 seconds.
- Using a diagnostic scan tool, perform the self-test.
- Retrieve the Diagnostic Trouble Codes (DTCs) from all modules.
Is DTC U0121:00 set in the BCM ?
Yes GO to A8. No GO to A9. - A8 CHECK FOR CORRECT ABS MODULE OPERATION
- Ignition OFF.
- Disconnect and inspect all ABS module connectors.
- Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary
- Reconnect all the ABS module connectors. Make sure they seat and latch correctly.
- Operate the system and determine if the concern is still present.
Is the concern still present?
Yes CHECK OASIS for any applicable TSBs. If a TSB exists for this concern, DISCONTINUE this test and FOLLOW the TSB instructions. If no TSBs address this concern, INSTALL a new ABS module. REFER to Anti-Lock Brake System (ABS) and Stability Control . No The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues. - A9 CHECK FOR CORRECT PCM OPERATION
- Ignition OFF.
- Disconnect and inspect all PCM connectors.
- Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary
- Reconnect all the PCM connectors. Make sure they seat and latch correctly.
- Operate the system and determine if the concern is still present.
Is the concern still present?
Yes CHECK OASIS for any applicable TSBs. If a TSB exists for this concern, DISCONTINUE this test and FOLLOW the TSB instructions. If no TSBs address this concern, INSTALL a new PCM. REFER to Powertrain Control Module (PCM) . No The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.