Diagnostic session flow testing
Test entry, behavior, and continuity of diagnostic sessions against the expected ECU communication flow.
Vehicle Diagnostics
Diagnostic Session Testing for ECU Communication
Exercise ECU diagnostic sessions against expected service flows, investigate session failures and unexpected UDS negative responses, and turn defined diagnostic behavior into repeatable tests or a focused diagnostic application.
Discuss a Diagnostic Session ProjectProblems I can investigate
Find the behavior behind the symptom
- 01
Diagnostic session failure
Determine why an ECU does not enter or remain in the required diagnostic session, including behavior related to service availability and timing.
- 02
Unexpected UDS negative response
Analyze where an ECU returns a negative-response code that does not match the expected diagnostic flow, using repeatable communication and response checks.
What I can help with
Focused engineering work in Vehicle Diagnostics
UDS response analysis
Exercise UDS services and compare observed responses with the supplied diagnostic expectations, including focused analysis of negative responses.
Transport and network coverage
Build test coverage for diagnostic communication carried through ISO-TP or DoIP where those transports are part of the supplied setup.
Protected-service testing
Include security access in diagnostic session tests when the required challenge-response behavior and test inputs are available.
Automated test implementation
Develop repeatable diagnostic tests and assertions in CANoe and CAPL where those tools are available in the engineering environment.
Diagnostic application development
Create a focused application for executing and interpreting ECU diagnostic services using the available diagnostic descriptions and communication context.
What to send
Start with the evidence you already have
ECU
The ECU available for communication or testing, together with the diagnostic behavior to be exercised.
ODX
The ASAM diagnostic-data description used to define relevant diagnostic services, data, and expected behavior.
PDX
The packaged exchange containing ODX diagnostic data for the ECU or diagnostic scope.
Problem description
Observed symptoms, context, reproduction steps, and expected behavior for the diagnostic session or UDS response issue.
How the analysis works
From recorded data to engineering findings
- 01
Review the diagnostic scope
Examine the ECU, ODX or PDX data, problem description, and expected diagnostic session behavior.
- 02
Define the test flow
Map the required UDS communication sequence, relevant DIDs, routine control activity, security access needs, and expected responses.
- 03
Exercise the ECU
Run focused tests across the applicable diagnostic session and transport setup, recording behavior that differs from the expected flow.
- 04
Analyze failures
Compare session transitions, timing, diagnostic data, and UDS negative responses to identify a likely area for further investigation without assuming a root cause.
- 05
Package the engineering result
Provide repeatable tests or a focused diagnostic application with clear execution context and interpretation of observed ECU behavior.
What you receive
Deliverables matched to the investigation
Automated test suite
Executable tests with assertions, setup, and repeatable results for the defined diagnostic session and UDS response flows.
Diagnostic application
Software for executing and interpreting the ECU diagnostic services within the agreed diagnostic scope.
Technologies & formats
Automotive data and analysis environments
- Diagnostic Session
Diagnostic Session
An ECU diagnostic operating mode controlling service availability and timing.
- UDS
Unified Diagnostic Services
ISO 14229 diagnostic services for communicating with vehicle ECUs.
- Security Access
Security Access
A diagnostic challenge-response mechanism that unlocks protected ECU services.
- ISO-TP
ISO 15765-2 Transport Protocol
A segmented transport protocol for messages carried over CAN.
- DoIP
Diagnostics over Internet Protocol
Diagnostic transport over IP networks as defined by ISO 13400.
- DTC
Diagnostic Trouble Code
A coded diagnostic record identifying a detected fault condition.
- DID
Data Identifier
A UDS identifier addressing diagnostic data exposed by an ECU.
- Routine Control
Routine Control
The UDS service used to start, stop, or request results from ECU routines.
- CANoe
Vector CANoe
A development, simulation, test, and analysis environment for vehicle networks.
- CAPL
Communication Access Programming Language
Vector event-driven language for network simulation, testing, and automation.
- DCM
Diagnostic Communication Manager
The Classic AUTOSAR basic-software module handling diagnostic communication.
FAQ
Practical questions before an investigation
- What diagnostic session issues can be tested?
- The work can focus on an ECU that does not enter or remain in the required diagnostic session, including behavior related to the expected service flow and timing.
- Can testing include unexpected UDS negative responses?
- Yes. Tests can capture and assess negative responses against the expected diagnostic flow, using the supplied ECU behavior and diagnostic data.
- Can ODX and PDX data be used to define the tests?
- Yes. ODX or PDX can provide the diagnostic descriptions used to establish relevant services, data, and expected behavior.
- Can the work use CANoe and CAPL?
- Where they are available in the engineering environment, CANoe and CAPL can support diagnostic test automation, simulation, and analysis.
Discuss the evidence
Discuss a Diagnostic Session Project
Share the ECU, ODX or PDX data, and problem description to scope a focused diagnostic session testing activity.