Pinpoint Test Ar: U0121:00
WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
- Normal Operation and Fault Conditions
The RCM uses information contained in messages from the ABS sent on the HS-CAN2.
DTC Fault Trigger Conditions
DTC Description Fault Trigger Condition RCM U0121:00 Lost Communication With Anti-Lock Brake System (ABS) Control Module "A": No Sub Type Information This DTC sets if the RCM does not receive an expected message from the ABS control module. Possible Sources
- Network traffic
- ABS
- RCM
- WARNING: Do not handle, move or change the original horizontal mounting position of the Restraints Control Module (RCM) while the Restraints Control Module (RCM) is connected and the ignition switch is ON. Failure to follow this instruction may result in the accidental deployment of the Safety Canopy® and cause serious personal injury or death.
- NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test.
- NOTE: SRS components should only be disconnected or reconnected when instructed to do so within a pinpoint test step. Failure to follow this instruction may result in incorrect diagnosis of the SRS.
- NOTE: Always make sure the correct SRS component is being installed. Parts released for other vehicles may not be compatible even if they appear physically similar. Check the part number listed in the Ford parts catalog to make sure the correct component is being installed. If an incorrect SRS component is installed, Diagnostic Trouble Codes (DTCs) may set.
- NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer.
- AR1 CHECK THE COMMUNICATION NETWORK
-
WARNING: Before beginning any service procedure In this article, refer to Safety warnings in General Information. Failure to follow this instruction may result in serious personal injury.
REFER to: Pyrotechnic Device Health and Safety Precautions .
- Ignition ON.
- Using a diagnostic scan tool, carry out a network test.
Does the ABS pass the network test?
Yes GO to AR2 No To diagnose no communication with the ABS, REFER to: Controller Area Network (CAN) Module Communications Network . -
- AR2 CHECK THE RCM (RESTRAINTS CONTROL MODULE) CONTINUOUS MEMORY DIAGNOSTIC TROUBLE CODES (CMDTCS)
- Ignition ON.
- Using a diagnostic scan tool, perform RCM self-test.
- Using a diagnostic scan tool, clear RCM Diagnostic Trouble Codes (DTCs).
- Wait 10 seconds.
- Using a diagnostic scan tool, perform RCM self-test.
Is DTC U0121:00 retrieved again?
Yes GO to AR3 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. - AR3 RETRIEVE THE RECORDED DIAGNOSTIC TROUBLE CODES (DTCS) FROM THE RCM (RESTRAINTS CONTROL MODULE) SELF-TEST
- Check the recorded Diagnostic Trouble Codes (DTCs) from the RCM self-test.
Is DTC U3003:16 or U3003:17 recorded?
Yes GO to Pinpoint Test BD No GO to AR4 - AR4 RETRIEVE THE RECORDED DIAGNOSTIC TROUBLE CODES (DTCS) FROM THE ABS (ANTI-LOCK BRAKE SYSTEM) SELF-TEST
- Using a diagnostic scan tool, perform ABS self-test.
- Check for recorded Diagnostic Trouble Codes (DTCs) from the ABS self-test.
Is ABSDTC U3003:16 or U3003:17 recorded?
Yes REFER to: Anti-Lock Brake System (ABS) and Stability Control . No GO to AR5 - AR5 CHECK FOR DTC (DIAGNOSTIC TROUBLE CODE) U0121:00 SET IN OTHER MODULES
- Ignition ON.
- Using a diagnostic scan tool, perform self-test for all modules.
Is DTC U0121:00 set in the BCM or in the IPC?
Yes CHECK OASIS for any applicable service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, INSTALL a new ABS control module. REFER to: Anti-Lock Brake System (ABS) Module . No CHECK OASIS for any applicable service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, INSTALL a new RCM. REFER to: Restraints Control Module (RCM) .