Vehicle Diagnostics or Automotive Diagnostics
The automobile as we know it was not invented in a single day or a single man. It is a complex machine that has over a century of innovation.
Detecting a failure in this complex machine would be a difficult task. However, most of the vehicles today include ECU (Electronic Control Unit (ECU)), which connected several sensors, it will always monitor the sensor value, located throughout the engine, fuel and wheel speed, exhaust systems. When the ECU in the vehicle detects a fault or a problem, First, a warning light on the dashboard is set, to inform the driver that some problem is there in the vehicle. Second, the code is recorded in the ECUs memory EEPROM so that it can later be retrieved by a technician for repair,That code are DTC codes,
Detecting a failure in this complex machine would be a difficult task. However, most of the vehicles today include ECU (Electronic Control Unit (ECU)), which connected several sensors, it will always monitor the sensor value, located throughout the engine, fuel and wheel speed, exhaust systems. When the ECU in the vehicle detects a fault or a problem, First, a warning light on the dashboard is set, to inform the driver that some problem is there in the vehicle. Second, the code is recorded in the ECUs memory EEPROM so that it can later be retrieved by a technician for repair,That code are DTC codes,
What is Vehicle Diagnostics
Diagnostics, as the word suggests, is to identify the problem or a situation of the vehicle. Whenever the ECU finds a problem, it stores that problem as a Diagnostics Trouble Code (DTC) in the EEPROM for later retrieval. Diagnostic Tools are used to read data (DTC’s) from the EEPROM to analyse the cause of failureAutomotive Diagnostics :
- Diagnostics Protocol
- Diagnostics Session
- Diagnostic Service
Diagnostics Protocol :
Protocol refers to a set of rules for communication used to communicate with ECU to diagnostic tool .The protocols which are used for Diagnostics purposes are known as Diagnostics Protocol.
Example :
CAN (Control Area Network),
K-Line,
UDS (Unified Diagnostics Services),
K-Line,
UDS (Unified Diagnostics Services),
KWP (Keyword Protocol).
Diagnostics Session:
Each diagnostics service have different timing property,means $22 service Read data by identifier have different timing property,it have limitation of time of work.Different types of diagnostics sessions like Default Session, Extended Diagnostic Session and ECU Programming Session.
Each diagnostics service have different timing property,means $22 service Read data by identifier have different timing property,it have limitation of time of work.Different types of diagnostics sessions like Default Session, Extended Diagnostic Session and ECU Programming Session.
When ECU is Switched ON that time ECU is in Default Session,$22 will work only Extended Session that time you have to go Extended Session By sending $10 $03.But Extended Session has time limit of 100ms after that it will come to Default Session.
Like this ECU Programming Session also have time limit and engineering session also have time limits.
Diagnostic Service:
Diagnostic Service are different type of service that helps technician to read the diffrent type of data and write the data and analyses the data.It will tell what’s wrong with the vehicle if it is not running or behaving improperly. Diagnosing a vehicle's problem in order to fix or repair a car can be done through a professional automobile diagnostic centre. Diagnostic Service uses the read command for retrieving the information/data from ECU and the write command to write/program the data to the ECU.
Diagnostic addressing:
When communicating with the ECU, the diagnostic tool uses either Physical addressing or Functional addressing method.
Physical addressing
Physical addressing is the kind of addressing where the Diagnostics tool communicates with a single ECU which address you have.
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