U0100 Toyota Code - Lost Communication with Engine Control Module
|Code U0100 Toyota Possible Causes
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
Faulty Controller Area Network (CAN) Communication System
Faulty Control Module
Control Module harness is open or shorted
Control Module circuit poor electrical connection
|Code U0100 Toyota Tech Notes
When there are problems with the way different systems in a vehicle communicate with each other using a technology called Controller Area Network (CAN) communication, Diagnostic Trouble Codes (DTC) are displayed. These codes can be caused by issues with the main bus or branch of the communication network, or with the Electronic Control Units (ECUs) and sensors that make up the different systems. If you see code for both the CAN communication problems and internal or power source problems at the same time, you should focus on fixing the internal or power source problems first.
|What are Code U0100 Toyota Possible Symptoms?
Engine Light ON (or Service Engine Soon Warning Light)
|Code U0100 Toyota Description
The Controller Area Network (CAN) is a standard bus system in vehicles that enables the connection of automotive devices without the need for a host computer. The exchange of operating information and commands among devices is facilitated by pre-programmed information about the required message exchange on the serial data circuits. Communication is carried out using two dedicated wires, known as CAN high and CAN low, with both lines carrying 2.5V when the CAN bus is in idle mode. During the transmission of data bits, the CAN high line increases to 3.75V while the CAN low drops to 1.25V, creating a 2.5V differential between the lines. Since communication relies on a voltage differential between the two bus lines, the CAN bus is NOT sensitive to inductive spikes, electrical fields, or other noise. The Diagnostic Trouble Code (DTC) sets when a message that includes the transmitter device availability has not been received.