ECU communication - lack of connection between modules and how to diagnose
Lack of communication between modules is one of the most common problems in modern cars. ECU, TCU, ABS, ESP, BCM and dashboard exchange information via CAN and LIN lines. When the connection is broken, the diagnostics does not detect modules, and the car may not start at all.
Typical symptoms
The diagnostics does not find the ECU or ABS;
The car doesn't start even though the dashboard is lit;
The dashboard is missing rpm and temperature;
Error "U0001 - CAN Bus Communication Fault".
Main reasons
Burned CAN transceiver ;
Damaged 5V regulator;
Short between CAN-H and CAN-L;
No KL30 power supply to the ECU;
Broken track or oxidized pin in connector.
