Pinpoint Test An: DTC U0121

AN1 VERIFY CUSTOMER CONCERN
- Ignition ON.
- Verify that there is an observable symptom present.
- Is an observable symptom present?
  - Yes : GO to AN2.
  - 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.
AN2 CHECK THE COMMUNICATION NETWORK
- Enter the following diagnostic mode on the scan tool: Network Test.
- Carry out the network test.
- Does the ABS module pass the network test?
  - Yes : GO to AN3.
  - No : REFER to MODULE COMMUNICATIONS NETWORK article.
AN3 RETRIEVE THE RECORDED DTCs FROM THE SELF-TEST
- Check for recorded IC DTCs from the self-test.
- Is DTC B1317 or DTC B1318 recorded?
  - Yes : For DTC B1317, GO to PINPOINT TEST AK .
    For DTC B1318, GO to PINPOINT TEST AL .
  - No : GO to AN4.
AN4 RECHECK THE IC 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.
- Clear the DTCs. Repeat the IC self-test.
- Is DTC U0121 still present?
  - Yes : INSTALL a new PCM. REFER to ENGINE CONTROLS - ELECTRONIC ENGINE CONTROLS article. TEST the system for normal operation. REPEAT the PCM self-test.
    If DTC U0121 is still present, INSTALL a new IC module.
  - 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.