In this article, we will first discuss the Diagnostic SID range, the UDS services list, and the different diagnostic protocols (UDS, SAE J1979 OBD-II) associated with them. Next, we will explain how each Service Identifier maps to a specific protocol, since this is essential for streamlining diagnostic tool development and ensuring compatibility with various ECUs. Finally, it is necessary to recognize which SIDs are reserved, standardized, or OEM-specific. Consequently, this understanding ensures accurate implementation and results in smoother troubleshooting.
Table of Contents
What is a Diagnostic SID (Service Identifier)?
A Diagnostic SID (Service Identifier) is used in vehicle diagnostic protocols to represent a specific service or function associated with vehicle ECUs. Specifically, it is a numerical or alphanumeric code. For example, Service Identifier $10 corresponds to Diagnostic Session Control in the UDS protocol.
Moreover, the Diagnostic SID range defines a category of SID values associated with any diagnostic protocol.
SIDs, which are integral components of standardized diagnostic protocols such as OBD-II (On-Board Diagnostics II) and UDS, play a crucial role in vehicle diagnostics. They are used to request information from, or send commands to, ECUs.
Each SID corresponds to a diagnostic service, like reading sensor data, clearing DTCs, conducting system tests, or accessing ECU parameters.
Diagnostic tools or scanners use these SIDs to communicate with the ECUs and perform diagnostic tasks.
What is a vehicle Diagnostic Protocol?
A vehicle diagnostic protocol refers to a communication protocol used by vehicle ECUs to interact with a diagnostic tool or vehicle scanner tool. Specifically, these protocols enable technicians and engineers to identify and diagnose issues within the vehicle. For instance, such issues may include engine performance problems, transmission malfunctions, ABS (Anti-lock Braking System) faults and more.
Unified Diagnostic Services (UDS) and SAE J1979 (OBD-II) protocol are examples of vehicle diagnostic protocols.
Diagnostic Service Identifier (SID) range overview (0x00 – 0xFF)
Let’s discuss about the SID range and associated Diagnostic Services:
| SID Range (hex) | Service Type | Standard Name |
|---|---|---|
| $00 – $0F | OBD Requests (SAE J1979 OBD-II) | ISO 15031-5 |
| $10 – $3E | UDS Requests | ISO 14229-1 |
| $3F | Not Applicable (N.A.) | Reserved |
| $40 – $4F | OBD Response | ISO 15031-5 |
| $50 – $7E | UDS Response | ISO 14229-1 |
| $7F | Negative Response | ISO 14229-1 |
| $80 | Reserved | ISO 14229-1 |
| $81 – $82 | Reserved | ISO 14230 |
| $83 – $87 | UDS Requests | ISO 14229-1 |
| $88 – $9F | Requests | Reserved for Future definition |
| $A0 – $B9 | Requests | Defined by Vehicle Manufactures (OEM) |
| $BA – $BE | Requests | Defined by Suppliers |
| $BF | N.A. | Reserved |
| $C0 | Reserved | ISO 14229-1 |
| $C1 – $C2 | Reserved | ISO 14230 |
| $C3 – $C7 | Positive Response | ISO 14229-1 |
| $C8 – $DF | Positive Response | Reserved for Future definition |
| $E0 – $F9 | Positive Response | Defined by Vehicle Manufacturers (OEM) |
| $FA – $FE | Positive Response | Defined by Suppliers |
| $FF | N.A. |
As seen above, the Diagnostic Service Identifier (SID) range defines Diagnostic requests and responses for UDS and OBD-II protocols. Some of the values reserve for future use. This list is useful to quickly identify the Diagnostic protocol involved based on the Diagnostic Service Identifier.
Additionally, it helps engineers and developers separate mandatory services from optional ones supported by a given ECU. Consequently, understanding SID allocation is essential since it allows for the design of diagnostic tools that are compliant and interoperable.
