Pinpoint Test Ab: 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.
- AB1 REPEAT THE ON-DEMAND SELF-TEST
- Key in ON position.
- Enter the following diagnostic mode on the diagnostic tool: HCM Self-Test
- Clear the DTCs and repeat the HCM on-demand self-test.
- Is DTC U0100 retrieved again?
- YES : Go to AB2.
- NO : The vehicle is operating correctly at this time. The HCM may have temporarily lost communication with the PCM.
- AB2 CHECK OTHER MODULES FOR DTC U0100
- Enter the following diagnostic mode on the diagnostic tool: Instrument Cluster (IC) Self-Test
- Carry out the on-demand self-test for other modules on the high speed controller area network (HS-CAN). The IC, ABS module and restraints control module (RCM), for example, communicate on the HS-CAN.
- Is DTC U0100 retrieved from any other module?
- AB3 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?
- YES : INSTALL a new PCM. REFER to ELECTRONIC ENGINE CONTROLS . TEST the system for normal operation.
- NO : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
- AB4 CHECK FOR CORRECT HCM OPERATION
- Disconnect the HCM connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the HCM connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
- YES : INSTALL a new HCM. REFER to Headlamp Control Module (HCM) in this. TEST the system for normal operation.
- NO : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.