UDS (Unified Diagnostic Services) Tutorials For Automotive Engineers

December 27, 2023December 27, 2023 CS Electrical And Electronics

Hello guys, welcome back to our blog. Here in this article, we will discuss UDS (Unified Diagnostic Services), the different main services in UDS, and why it is used with its applications.

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UDS (Unified Diagnostic Services) Tutorials For Automotive Engineers

Unified Diagnostic Services (UDS) is a communication protocol utilized in the automotive sector for diagnostic communication between electronic control units (ECUs) within vehicles. It’s part of the On-Board Diagnostics (OBD) standards and serves the purpose of diagnostics, maintenance, and reprogramming in modern vehicles.

UDS facilitates the interaction between a diagnostic tool (such as a scan tool) and the vehicle’s ECUs. Its primary functions include retrieving diagnostic trouble codes, accessing sensor data, conducting component tests, and configuring ECUs.

Key elements of UDS encompass:

Diagnostic Session Control: UDS manages different diagnostic sessions to regulate communication between the diagnostic tool and the ECUs. These sessions define varying levels of access and available services.

Diagnostic Services: UDS defines a standardized set of diagnostic services that enable the diagnostic tool to request specific actions or data from the ECUs. These services involve tasks like reading trouble codes, accessing parameters, running tests, etc.

Communication Protocols: UDS can function across different communication protocols such as CAN, LIN, and FlexRay, adapting to diverse vehicle hardware interfaces.

Security Measures: UDS incorporates security mechanisms to ensure that only authorized diagnostic tools can access sensitive information or execute critical operations on the vehicle’s ECUs.

UDS is fundamental in contemporary vehicle diagnostics, empowering technicians to effectively diagnose issues, carry out maintenance tasks, and guarantee optimal vehicle performance by interacting with the vehicle’s electronic systems.

As vehicles continue to advance with sophisticated electronic systems, UDS evolves to meet the demands of diagnostics, providing enhanced capabilities for identifying, troubleshooting, and resolving vehicle issues.

01. Diagnostic Session Control (SID 10):

Diagnostic Session Control (SID 10) service is a fundamental part of the Unified Diagnostic Services (UDS) protocol used in the automotive industry for diagnostic purposes. This service is responsible for managing the establishment, maintenance, and termination of diagnostic sessions between a diagnostic tester (like a scan tool or diagnostic software) and an Electronic Control Unit (ECU) within a vehicle.

Here’s a detailed breakdown of its functionalities:

Session Establishment: When initiating communication with an ECU, the diagnostic tool starts by establishing a diagnostic session. This session could be of various types, including default, programming, extended, or specific manufacturer-defined sessions. Each type serves different purposes, such as general diagnostics, ECU reprogramming, or advanced diagnostic operations.

Session Control: Once the session is established, SID 10 controls the parameters of the diagnostic session. It manages communication settings like baud rates, timing parameters, and other configurations necessary for effective communication between the diagnostic tool and the ECU.

Session Termination: After the diagnostic operations are completed, the SID 10 service handles the termination of the session. This involves closing the communication link between the diagnostic tool and the ECU, releasing resources, and preparing for potential future sessions.

Error Handling: SID 10 also manages error handling during the session. It deals with any unexpected situations that might arise during communication, ensuring that proper error codes or responses are transmitted if communication issues occur.

Session Modes: Within the UDS protocol, different session modes can be employed, such as Default Session (used for standard diagnostics), Programming Session (for ECU reprogramming), Extended Session (for extended diagnostic functions), and others. SID 10 helps switch between these modes based on the requirements of the diagnostic process.

Security and Access Control: Depending on the capabilities of the specific ECU and the security measures in place, SID 10 might also manage security-related aspects, ensuring that the diagnostic tool has the necessary permissions and access rights to communicate with and control the ECU.

In summary, SID 10 is the gateway service that initiates, regulates, and concludes diagnostic sessions between a diagnostic tool and the vehicle’s ECUs. It ensures that the communication is established correctly, parameters are configured appropriately, operations are carried out smoothly, and the session is terminated in an organized manner. This service is crucial for effective and controlled diagnostic operations within the automotive environment.

02. ECU Reset (SID 11):

The ECU Reset service (Service Identifier 11 in Unified Diagnostic Services – UDS) plays a vital role in the diagnostic capabilities of automotive systems. Its primary function is to reset Electronic Control Units (ECUs) within a vehicle to either a default state or a specified state. This reset process can be crucial for troubleshooting issues, initializing components, or preparing the system for certain operations.

Here’s a detailed breakdown of the ECU Reset service:

Reset Types: SID 11 allows for different types of resets:

Hard Reset: Resets the ECU completely, returning it to its default factory state. This erases all stored data and configurations, restoring the ECU to its initial settings.
Selective Reset: Allows resetting specific parts or functionalities within the ECU. It might reset certain parameters, adaptation values, or specific subsystems without affecting the entire ECU.

Fault Clearing: One of the primary purposes of using the ECU Reset service is to clear fault codes or error conditions that might be stored in the ECU’s memory. Resetting the ECU often clears transient faults or errors that might not require immediate attention.

Adaptation Reset: Some ECUs have adaptive learning capabilities, where they adjust parameters based on driving conditions or usage patterns. The ECU Reset service can reset these adaptations, allowing the ECU to relearn and readjust based on new conditions.

Initialization: Resetting an ECU can also serve as an initialization step for certain components or systems. For instance, after replacing a part or performing maintenance, resetting the related ECU might be necessary to ensure proper functioning.

Reprogramming Preparation: In cases where ECU reprogramming is required, a reset might be necessary to prepare the ECU for new software or firmware updates.

System Stability: Occasionally, certain issues within the vehicle’s systems might lead to performance degradation. Resetting the ECU can help stabilize the system by clearing any anomalies that might have occurred.

Precautions: It’s important to note that while an ECU reset can resolve certain issues, it might also cause the loss of stored data or configurations. Therefore, it should be used judiciously and with caution, ensuring that critical information or settings are backed up if needed.

Diagnostic Utility: This service is a vital tool for diagnostics, allowing technicians to perform troubleshooting steps, clear faults, and ensure that systems are operating as intended.

In summary, the ECU Reset service (SID 11) is an essential tool within the UDS protocol, allowing for the controlled resetting of Electronic Control Units within a vehicle. It’s used for fault clearing, adaptation reset, system stabilization, and preparation for various maintenance and diagnostic procedures.

03. Read Data By Identifier (SID 22):

The “Read Data By Identifier” service (Service Identifier 22 in Unified Diagnostic Services – UDS) is a critical functionality within automotive diagnostics. This service allows a diagnostic tool to request specific diagnostic data from an Electronic Control Unit (ECU) in a vehicle by using predefined identifiers. These identifiers serve as standardized references for various parameters, sensor readings, statuses, or information stored within the ECU.

Here’s a detailed breakdown of the Read Data By Identifier service:

Identifier Structure: Each identifier is a unique numerical value or code that represents a particular parameter or set of data within the ECU. These identifiers are standardized and documented according to industry standards or manufacturer-specific protocols. For instance, an identifier might represent a specific sensor reading, a control setting, or a system status.

Requesting Data: When the diagnostic tool initiates communication with the ECU and invokes SID 22, it sends the specific identifier(s) it wants to read from the ECU. This request specifies what data the diagnostic tool is interested in retrieving.

Data Retrieval: Upon receiving the request with the identifier(s), the ECU processes the request and retrieves the corresponding data associated with the provided identifier(s). This data might include sensor values, operational parameters, diagnostic trouble codes (DTCs), status information, or other relevant data stored within the ECU’s memory.

Data Format: The data retrieved from the ECU might be in various formats, such as raw hexadecimal values, calibrated values, or human-readable units (like temperature in Celsius). The diagnostic tool interprets this data based on the identifier and displays it in a user-friendly format for analysis or troubleshooting purposes.

Diagnostic Applications: SID 22 is extensively used during diagnostic procedures. It allows technicians to access specific information about the vehicle’s systems, aiding in fault diagnosis, performance analysis, system verification, and calibration adjustments.

Standardization: The use of standardized identifiers across vehicles and manufacturers streamlines the diagnostic process, enabling compatibility between diagnostic tools and various ECUs across different vehicle models and brands.

Real-time Data: Some data requested via SID 22 can provide real-time information, allowing technicians to monitor system parameters while the vehicle is in operation. This real-time data can aid in diagnosing intermittent faults or assessing system performance.

Versatility: This service is versatile and can cover a wide range of data types, making it a fundamental aspect of diagnostic communications, and providing insights into the health and performance of vehicle systems.

In summary, the Read Data By Identifier service (SID 22) facilitates the retrieval of specific diagnostic data from an ECU using standardized identifiers. It’s a crucial tool for diagnostics, enabling technicians to access relevant information needed for troubleshooting, maintenance, and analysis of vehicle systems.

04. Read Data By Address (SID 23):

The “Read Data By Address” service (Service Identifier 23 in Unified Diagnostic Services – UDS) is a diagnostic functionality used in automotive systems, enabling a diagnostic tool to read specific data from an Electronic Control Unit (ECU) in a vehicle by addressing the memory locations directly.

Here’s a detailed breakdown of the Read Data By Address service:

Memory Addressing: Unlike Read Data By Identifier (SID 22) and Read Scaling Data By Identifier (SID 24) which retrieve information based on standardized identifiers, SID 23 retrieves data directly from specified memory addresses within the ECU.

Data Retrieval: The diagnostic tool sends requests to the ECU, specifying the exact memory addresses from which it needs to retrieve data. These addresses might correspond to specific registers, locations, or blocks within the ECU’s memory where relevant information is stored.

Raw Data Access: SID 23 enables direct access to raw data stored in the memory locations of the ECU. This raw data might include various parameters, configuration settings, sensor readings, or other critical information stored in specific memory locations.

Data Format: The data retrieved through SID 23 is typically in its raw form, often represented in hexadecimal or binary format. Unlike SID 22 or SID 24, which provide interpreted or scaled data, the data retrieved using SID 23 might require further interpretation or decoding by the diagnostic tool.

Diagnostic Use: This service is often utilized by advanced diagnostic tools or during specific troubleshooting scenarios where direct access to raw data in the ECU’s memory is necessary. It allows technicians to access detailed information that might not be accessible through standardized identifiers.

Advanced Operations: SID 23 can be employed for advanced diagnostic operations, system analysis, or when specific data stored at precise memory locations needs to be examined or modified during diagnostics or ECU reprogramming processes.

Cautionary Note: Direct access to memory addresses should be performed with caution as manipulating certain data or settings within the ECU’s memory without proper knowledge or authorization can lead to system malfunctions or unintended consequences.

Specialist Use: This service might be more commonly used by advanced technicians, engineers, or diagnostic specialists due to its technical nature and the need for a deep understanding of ECU memory structure and data storage.

In summary, the Read Data By Address service (SID 23) provides a means for diagnostic tools to directly access specific memory locations within an ECU to retrieve raw data. It offers a deeper level of access to ECU data, allowing for more detailed analysis and advanced diagnostic procedures when necessary.

05. Read Scaling Data By Identifier (SID 24)

The “Read Scaling Data By Identifier” service (Service Identifier 24 in Unified Diagnostic Services – UDS) is a significant functionality within automotive diagnostics, particularly when the diagnostic tool requires human-readable or calibrated values from an Electronic Control Unit (ECU) in a vehicle. This service allows a diagnostic tool to request specific diagnostic data in a more user-friendly format using standardized identifiers.

Let’s break down the Read Scaling Data By Identifier service:

Purpose: SID 24 serves a similar function to the Read Data By Identifier service (SID 22), but with a crucial difference. Instead of retrieving raw or hexadecimal values, this service is specifically designed to retrieve scaled or converted diagnostic data in a human-readable or calibrated format.

Scaled Data: The data retrieved via SID 24 is scaled or converted from the raw values stored in the ECU’s memory. For instance, if the ECU stores a temperature reading in a specific range of raw values, the SID 24 service would retrieve this data and present it in a familiar temperature scale, such as Celsius or Fahrenheit.

Identifier Usage: Just like SID 22, SID 24 relies on standardized identifiers that represent specific parameters or data sets within the ECU. These identifiers allow the diagnostic tool to request the desired scaled data from the ECU.

Calibration Factors: To convert raw values into scaled or calibrated data, ECUs often store calibration factors or conversion formulas. When SID 24 is invoked, the ECU uses these factors to convert the raw data into human-readable or calibrated values before transmitting it to the diagnostic tool.

Diagnostic Applications: This service is particularly useful when technicians need easily interpretable data for analysis, troubleshooting, or system evaluation. For example, it might retrieve sensor readings, pressure values, temperature measurements, or other critical parameters in understandable units.

Real-time Monitoring: Similar to SID 22, SID 24 can provide real-time scaled data, allowing technicians to monitor and analyze system parameters while the vehicle is operational. This capability aids in diagnosing faults and assessing the health and performance of vehicle systems.

Standardization and Compatibility: The use of standardized identifiers ensures compatibility between diagnostic tools and various ECUs across different vehicle models and manufacturers. This standardization streamlines the diagnostic process and promotes interoperability between diagnostic equipment.

In summary, the Read Scaling Data By Identifier service (SID 24) allows diagnostic tools to retrieve scaled or converted diagnostic data from an ECU using standardized identifiers. It provides human-readable or calibrated values, making the retrieved data more user-friendly and facilitating analysis, troubleshooting, and maintenance of vehicle systems.

06. Security Access (SID 27):

The “Security Access” service (Service Identifier 27 in Unified Diagnostic Services – UDS) is a crucial component of automotive diagnostics, particularly in dealing with secured functionalities within Electronic Control Units (ECUs) in vehicles. This service facilitates the authorization and access to protected or secure diagnostic functions within an ECU.

Let’s delve into the details of the Security Access service:

Protected Functionalities: Some ECUs in vehicles contain sensitive or critical functionalities that are protected by security measures. These could include advanced settings, programming options, sensitive data, or functionalities crucial for the vehicle’s security and operation.

Access Authorization: SID 27 is used to grant permission or access rights to these secured functionalities within the ECU. The diagnostic tool sends a request for security access to the ECU along with a security key or credentials required for authorization.

The abbreviations AS, ENG, EOL, IO_AS, and IO_EOL typically refer to different levels or stages within the automotive development or manufacturing process. These levels are often associated with different phases of assembly, testing, or engineering in the automotive industry. Here’s an overview of what each abbreviation might represent:

a. AS – Assembly:

Description: AS usually stands for Assembly, denoting a stage in the production process where individual components or subsystems are assembled to create larger systems or the final vehicle assembly.
Activities: This phase involves integrating various parts, modules, or components according to predefined procedures or assembly lines. It encompasses tasks like fitting parts, installing components, and ensuring the proper assembly of the vehicle.

b. ENG – Engineering:

Description: ENG typically refers to the Engineering phase, where design, development, and validation activities take place.
Activities: Engineering involves the creation, design, and testing of vehicle components, systems, or technologies. It includes tasks related to prototyping, testing new features, refining designs, and ensuring compliance with safety and performance standards.

c. EOL – End-of-Line:

Description: EOL stands for End-of-Line, marking the final stage of the assembly line where the completed vehicle undergoes comprehensive testing and quality checks before leaving the production line.
Activities: At the EOL stage, the vehicle is subject to various tests, including functional tests, quality inspections, performance verifications, and sometimes even road tests to ensure that the vehicle meets all the required standards before being released for shipment.

d. IO_AS – Input/Output Assembly:

Description: IO_AS might refer to Input/Output Assembly, which could indicate a specific step in the assembly process where input and output components or modules are integrated or connected.
Activities: This phase could involve integrating systems responsible for taking input signals (like sensors) and providing output responses (like actuators or display units) within the vehicle assembly.

e. IO_EOL – Input/Output End-of-Line:

Description: IO_EOL might represent a stage toward the end of the assembly line where the integration, calibration, or testing of input/output systems occurs before the final quality checks.
Activities: This stage could involve final checks and calibration of input/output systems, ensuring proper functioning and communication between various components and systems within the vehicle before it undergoes final testing.

These abbreviations are often used within the automotive industry to signify different phases or stages within the production, engineering, or testing processes. The specifics of these stages may vary between manufacturers or contexts, but they generally represent key steps in the lifecycle of vehicle development, assembly, or testing.

Security Mechanisms: The security key provided by the diagnostic tool could be in various forms, including encryption keys, access codes, cryptographic keys, challenge-response sequences, or other authentication methods established by the vehicle manufacturer.

Authorization Process: When the ECU receives the request for security access along with the provided security key, it verifies the authenticity and validity of the key. If the key matches the expected or authorized credentials, the ECU grants access to the protected functionalities.

Secure Operations: Once access is granted, the diagnostic tool gains the authority to perform specific secured operations within the ECU. These operations might involve advanced diagnostic functions, programming tasks, parameter adjustments, or configuration changes that are otherwise restricted.

Protection Against Unauthorized Access: The Security Access service is designed to prevent unauthorized entities or tools from accessing critical or sensitive functionalities within the vehicle’s ECUs. It ensures that only authorized diagnostic tools or personnel with the correct security keys can access protected features.

Diagnostic Use: This service is often used during advanced diagnostics, maintenance, programming, or repair operations that require access to secured functionalities within the ECUs. It’s particularly relevant when dealing with advanced systems or in-depth troubleshooting scenarios.

Manufacturer-Specific: Security access mechanisms can vary between vehicle manufacturers. Each manufacturer might implement its own security protocols and methods, making it crucial for diagnostic tools to support and comply with these specific security requirements.

In summary, the Security Access service (SID 27) is a critical component of the UDS protocol, enabling authorized access to secured functionalities within vehicle ECUs. It ensures that only authenticated diagnostic tools or authorized personnel can perform specific secured operations, maintaining the integrity and security of the vehicle’s electronic systems.

07. Communication Control (SID 28):

The “Communication Control” service (Service Identifier 28 in Unified Diagnostic Services – UDS) is an essential functionality within automotive diagnostics, responsible for managing and controlling the communication channel between a diagnostic tool and an Electronic Control Unit (ECU) in a vehicle.

Let’s break down the Communication Control service in detail:

Communication Management: SID 28 primarily deals with managing the communication link between the diagnostic tool (such as a scan tool or diagnostic software) and the ECU. It controls the initiation, suspension, and resumption of communication during the diagnostic session.

Session Control: This service helps in controlling the communication parameters and behavior during the diagnostic session. It manages aspects such as baud rates, message timing, protocol settings, and other communication parameters necessary for effective communication between the diagnostic tool and the ECU.

Initialization: When establishing communication with an ECU, the Communication Control service might handle the initialization process, ensuring that the communication link is established correctly and the parameters are configured appropriately for reliable data exchange.

Suspended Communication: Sometimes, during certain operations or conditions, it might be necessary to suspend communication temporarily. SID 28 allows for the suspension of communication without terminating the entire diagnostic session. This pause might occur during specific operations or when the ECU is engaged in critical tasks that require uninterrupted processing.

Resumption of Communication: After a communication suspension, the service facilitates the resumption of communication, allowing the diagnostic tool to continue exchanging data and commands with the ECU seamlessly.

Error Handling: The Communication Control service might also handle communication-related errors or issues that occur during the diagnostic session. It ensures that proper error codes or responses are transmitted if communication problems arise, helping in diagnosing and resolving communication-related issues.

Diagnostic Use: This service is crucial during diagnostic procedures, enabling controlled and effective communication between the diagnostic tool and the vehicle’s ECUs. It ensures that data exchange occurs smoothly and that diagnostic operations are carried out accurately.

Compatibility and Standards: SID 28 is defined according to industry standards, ensuring compatibility between different diagnostic tools and various ECUs across different vehicle models and manufacturers.

In summary, the Communication Control service (SID 28) is a critical component of the UDS protocol, responsible for managing the communication link between a diagnostic tool and an ECU during the diagnostic session. It ensures proper initialization, parameter configuration, error handling, and seamless data exchange, contributing to effective and controlled diagnostic operations within the automotive environment.

08. Tester Present (SID 3E):

The “Tester Present” service (Service Identifier 3E in Unified Diagnostic Services – UDS) is a fundamental functionality within automotive diagnostics. It allows an Electronic Control Unit (ECU) in a vehicle to detect and acknowledge the presence of a diagnostic tool or tester within the communication network.

Here’s a detailed breakdown of the Tester Present service:

Diagnostic Tool Identification: SID 3E is used by the diagnostic tool to inform the ECU that it is actively present and ready to communicate. It sends a “Tester Present” message to the ECU to announce its availability on the network.

Communication Initialization: When a diagnostic session begins, the diagnostic tool sends the Tester Present message to the ECU, indicating that it is connected and ready to perform diagnostic operations.

Session Management: This service helps in the initiation and establishment of the diagnostic session by indicating the presence of the diagnostic tool to the ECU. It ensures that the ECU recognizes the diagnostic tool’s readiness to communicate.

Connection Confirmation: The ECU, upon receiving the Tester Present message, acknowledges the presence of the diagnostic tool. This acknowledgment is essential for the diagnostic tool to proceed with sending diagnostic requests or commands to the ECU.

Session Continuity: During the diagnostic session, the diagnostic tool periodically sends Tester Present messages to maintain communication continuity. It serves as a way to ensure that the ECU knows the diagnostic tool is still active and ready to communicate.

Error Handling: If, for any reason, the ECU does not receive a Tester Present message when expected or encounters issues in communication with the diagnostic tool, it might trigger error codes or respond with communication-related error messages.

Diagnostic Use: SID 3E is an essential part of session management between the diagnostic tool and the vehicle’s ECUs. It ensures that the ECU acknowledges the presence of the diagnostic tool, allowing for proper communication and interaction during the diagnostic session.

Session Termination: When the diagnostic session concludes, the diagnostic tool might send a final Tester Present message or signal session termination to the ECU, indicating the end of the communication.

In summary, the Tester Present service (SID 3E) is used by the diagnostic tool to inform the ECU of its presence and readiness to communicate. It plays a crucial role in session initiation, continuity, and termination, ensuring proper communication between the diagnostic tool and the vehicle’s ECUs during the diagnostic process.

09. Routine Control (SID 31):

The “Routine Control” service (Service Identifier 31 in Unified Diagnostic Services – UDS) is a significant functionality within automotive diagnostics. It enables a diagnostic tool to initiate specific routines or tests within an Electronic Control Unit (ECU) in a vehicle, helping in diagnostic procedures, system testing, and control of various functions.

Here’s a detailed breakdown of the Routine Control service:

Routine Initiation: SID 31 allows the diagnostic tool to trigger predefined routines or tests within the ECU. These routines could include self-tests, actuator tests, sensor calibrations, or specific operations designed to verify or control various components or systems within the vehicle.

Diagnostic Routines: The routines initiated via SID 31 are specifically designed for diagnostic purposes. They aid in verifying the functionality, integrity, and performance of different systems or components within the vehicle.

Control of ECU Operations: This service provides the diagnostic tool with the capability to command the ECU to perform certain operations, activate specific components, or execute procedures that might not be part of regular vehicle operation.

Test and Verification: Routine Control facilitates the execution of tests that help verify the proper functioning of various vehicle systems, identify faults or issues, and aid in the diagnostic process.

Calibration and Adjustment: Some routines initiated through SID 31 might involve calibration procedures or adjustments to sensors, actuators, or other components. This enables fine-tuning or correcting deviations in system operation.

Advanced Diagnostics: Routine Control is often used in advanced diagnostics or during specific troubleshooting scenarios. It allows technicians to perform specialized tests or operations that aid in identifying and resolving complex issues within the vehicle’s electronic systems.

Safety and Performance Checks: Routines initiated by SID 31 can include safety checks or performance evaluations, ensuring that critical systems operate within specified parameters and meet safety standards.

Diagnostic Tool Commands: The diagnostic tool sends commands via this service to initiate, monitor, and control the execution of routines within the ECU, providing a means to interact with the vehicle’s systems for diagnostic purposes.

In summary, the Routine Control service (SID 31) in UDS is instrumental in enabling diagnostic tools to command and execute specific routines or tests within vehicle ECUs. These routines aid in diagnosing faults, verifying system functionality, performing adjustments, and conducting specialized tests to ensure the proper operation of various vehicle systems.

10. Control DTC Settings (SID 85):

The “Control DTC Settings” service (Service Identifier 85 in Unified Diagnostic Services – UDS) is a functionality within automotive diagnostics that allows a diagnostic tool to manage Diagnostic Trouble Codes (DTCs) stored in Electronic Control Units (ECUs) within a vehicle. DTCs are codes that indicate issues or faults within the vehicle’s systems.

Here’s a detailed breakdown of the Control DTC Settings service:

DTC Management: SID 85 enables the diagnostic tool to interact with the ECU to manage the storage, retrieval, and manipulation of DTCs. It allows control over how DTCs are handled within the ECU.

DTC Clearing: One of the primary functions of this service is to clear or reset DTCs stored in the ECU’s memory. Clearing DTCs removes the recorded fault codes, indicating that the issues triggering those codes have been addressed or resolved.

Selective DTC Clearing: In some cases, the diagnostic tool might provide options to selectively clear specific DTCs rather than clearing all stored codes. This selective approach can help focus on specific issues or components without erasing unrelated DTCs.

DTC Configuration: SID 85 might also enable configuration settings related to DTCs within the ECU. This could include enabling or disabling specific DTCs, configuring parameters associated with DTC storage or triggering thresholds, or setting DTC-related parameters according to specific requirements.

Status Readout: The service allows the diagnostic tool to read the status or information related to stored DTCs. This information might include details about the type of fault, the system or component affected, severity levels, and additional diagnostic information associated with each DTC.

Maintenance and Repair: Control DTC Settings is a valuable tool during maintenance and repair procedures. It helps technicians diagnose, address, and verify the resolution of issues by managing and interpreting DTCs effectively.

Error Monitoring: In some cases, the service might also monitor error conditions related to DTC management, such as issues in clearing codes, configuring settings, or handling DTC-related operations. Error codes might be triggered if problems occur during these processes.

Diagnostic Utility: SID 85 is used by diagnostic tools to perform DTC-related operations, ensuring efficient management and resolution of faults detected within the vehicle’s electronic systems.

In summary, the Control DTC Settings service (SID 85) provides the diagnostic tool with the capability to manage DTCs within an ECU, including clearing stored codes, configuring DTC-related settings, reading status information, and facilitating effective fault diagnosis and resolution within the vehicle’s electronic systems.

Each of these services plays a crucial role in facilitating effective communication and diagnostic operations between the diagnostic tool and the various ECUs in a vehicle, enabling efficient troubleshooting, maintenance, and repair of automotive systems.

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