U0100 - LOST COMMUNICATION WITH ECM / PCM
Description of DTC code U0100
The DTC U0100 OBDII code is set when signals are lost between the Engine Control Module (ECM) or Powertrain Control Module (PCM) and another particular control module. Maybe the Control Area Network (CAN) wiring may also have problems, resulting in a breakdown in communications.
The ECM / PCM is the vehicle's computer, which is in charge of engine management. It communicates through the Control Area Network so that all modules can communicate with each other. If the ECM or PCM cannot send or receive CAN communication signals, this code is set.
Symptoms of fault code U0100
- Check Engine light ON.
- The car has difficulty starting.
Causes of OBD2 U0100
Reasons why the U0100 OBD2 fault code is set:
- Damage in the Engine Control Module, Powertrain Control Module, or Transmission Control Module.
- Control Area Network communication failures.
- A computer component may have been installed for better performance, which may not be compatible with the wiring of one of the control modules or the CAN
- Computer connectors or cables improperly tightened.
Possible solutions of the DTC code U0100
The steps to solve the U0100 OBDII diagnostic code are:
- Check the Technical Service Bulletins available for your vehicle model.
- Check the system for broken, worn, or corroded wires. Repair as needed.
- Make sure the battery is fully charged. If it is not, you will have to make the necessary corrective actions.
- Use a digital multimeter to check that the CAN bus circuit is not shorted to ground or power. Take into account the multimeter must be connected between the two network pins on the data link connector. Note that there are two resistors at each end of the CAN bus. Check that both are working properly.
- A more advanced diagnosis will require the use of automotive scanner tools and a possible reprogramming of the PCM and, if necessary its replacement.