Pinpoint Test Ag: DTC U0100 - Lost Communication With ECM/Pcm

WARNING: This page is about a different car, the 2007 Lincoln MKX and 2007 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.

AG1 RETRIEVE THE RECORDED DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND INSTRUMENT CLUSTER SELF-TESTS
- Check for recorded instrument cluster DTCs from the continuous and on-demand self-tests.
- Is DTC B1318 recorded?
1. YES : Go to Pinpoint Test AD .
2. NO : Go to AG2.
AG2 RECHECK THE INSTRUMENT CLUSTER DTCs
- Clear the DTCs.
- Repeat the instrument cluster self-test.
- Is DTC U0100 still present?
1. YES : Go to AG3.
2. NO : The system is operating correctly at this time. The DTC may have been set due to high network traffic.
AG3 RETRIEVE THE RECORDED DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND ABS MODULE SELF-TESTS
- Check for recorded ABS module DTCs from the continuous and on-demand self-tests.
- Is DTC U0100 recorded?
1. YES : REFER to MODULE COMMUNICATIONS NETWORK article to diagnose no communication with the PCM.
2. NO : Go to AG4.
AG4 CHECK THE NETWORK OPERATION
- Carry out the network test.
- Does the PCM pass the network test?
1. YES : Go to AG5.
2. NO : REFER to MODULE COMMUNICATIONS NETWORK article to diagnose no communication with the PCM.
AG5 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Check for:
  - corrosion
  - damaged pins
  - pushed-out pins
- Connect all the PCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
1. YES : INSTALL a new PCM. REFER to ELECTRONIC ENGINE CONTROLS . TEST the system for normal operation.
2. NO : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.