Pinpoint Test N: U0121:00: U0121:00

• Ignition ON.
• Verify there is an observable symptom present.

Is an observable symptom present? 

• Yes  : GO to N2 
• No  : The system is operating normally at this time. The DTC  may have been set due to high network traffic or an intermittent fault condition.

• Using a diagnostic scan tool, perform the network test.

Does the ABS module pass the network test? 

• Yes  : GO to N3 
• No  : REFER to: COMMUNICATIONS NETWORK .

• Using a diagnostic scan tool, perform the 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 N4 

• Using a diagnostic scan tool, perform the GWM  self-test.

Are any Diagnostic Trouble Codes (DTCs) recorded? 

• Yes  : REFER to: COMMUNICATIONS NETWORK .
• No  : GO to N5 

• Using a diagnostic scan tool, clear the Diagnostic Trouble Codes (DTCs).
• Operate the system and test for normal operation.
• Check the Parking Aid Module (PAM) Continuous Memory Diagnostic Trouble Codes (CMDTCs).

Is DTC U0121:00 still present? 

• Yes  : GO to N6 
• 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.

• Using a diagnostic scan tool, clear all Diagnostic Trouble Codes (DTCs).
• Ignition OFF.
• Ignition ON.
• Wait 10 seconds.
• Using a diagnostic scan tool, retrieve the Continuous Memory Diagnostic Trouble Codes (CMDTCs) from all modules.

Is DTC U0121:00 or DTC U0121:87 set in any other module? 

• Yes  : INSTALL a new ABS  module.

  REFER to: HYDRAULIC CONTROL UNIT (HCU) .

• No  : INSTALL a new BCM  .

  REFER to: BODY CONTROL MODULE (BCM) .