Description
This session introduces the Vehicle Diagnostics to the learner. Diagnostics layer is a separate software layer in the Embedded ECU which is used to monitor ECU faults in real time and record them as DTCS. when the vehicle arrives service center, service center engineer can read all DTCs using special software by producing diagnostics requests. Diagnostics request are special CAN frame sent from the test software to the embedded ECU using specific can id defined by the OEM. Each ECU in the network has special ID for diagnostic request. upon receiving the request DUT will send the DTC status to the test software as response. The diagnostic communication usually follow UDS and OSEK TP standard for CAN bus. other purpose of Diagnostics is flashing ECU software. by default every ECU used have CAN diagnostic boot loader which can be activated upon session request. When ECU enter diagnostic programming session user can transfer binary file from the PC to DUT. other use of Diagnostic layer is ECU configuration. The ECU can be configured in extended diagnostic session. Modern vehicles have a diagnostic interface for off-board diagnostics, which makes it possible to connect a computer (client) or diagnostics tool, which is referred to as tester, to the communication system of the vehicle. Thus, UDS requests can be sent to the controllers which must provide a response (this may be positive or negative). This makes it possible to interrogate the fault memory of the individual control units, to update them with new firmware, have low-level interaction with their hardware (e. g. to turn a specific output on or off), or to make use of special functions (referred to as routines) to attempt to understand the environment and operating conditions of an ECU to be able to diagnose faulty or otherwise undesirable behavior.
