Understanding of DTC Failure Type Byte (FTB) Category
The DTC Failure Type Byte (FTB) Category Definition plays a pivotal role in diagnosing and addressing issues within a vehicle’s onboard computer systems.
DTC Failure Type Byte (FTB) Category Definition
Need of DTC FTB categories
When diagnosing automotive issues, technicians rely on a comprehensive list of DTC FTB categories to accurately classify and address faults within a vehicle’s electronic systems.
The onboard computer system uses a standardized list of DTC FTB categories to streamline the troubleshooting process, ensuring that each fault is categorized under the appropriate subtype for efficient and precise diagnosis.
Vehicle manufacturers often provide a detailed list of DTC FTB categories in their service manuals, helping technicians quickly identify the nature of a malfunction and apply the necessary fixes.
Different categories of DTC Failure Type Byte (FTB)
Below is the list of DTC Failure Type Byte (FTB) Category Definition
| FTB Category | FTB Category Name | FTB Category Description |
|---|---|---|
| 0x00 | General Failure Information | This category encompasses all other categories and is employed when the fault within a specific failure category is distinctive (cannot be standardized by introducing a new subtype), or when the identified fault is most accurately described by two or more subtypes within that particular Failure Category. |
| 0x01 | General Electrical Failures | This category comprises typical wiring failure modes, such as short circuits and open circuits, along with direct current (DC) properties governed by Ohm’s Law. |
| 0x02 | General Signal Failures | This category encompasses properties associated with the size, frequency, or rate of change, as well as the waveform shape. |
| 0x03 | FM (Frequency Modulated)/PWM (Pulse Width Modulated) Failures | This category encompasses issues associated with the Frequency Modulated (FM) and Pulse Width Modulated (PWM) inputs and outputs of the control module. It also covers faults in which position is determined by counts. |
| 0x04 | System Internal Failures | This category involves faults connected to memory, software, and internal electrical circuitry, necessitating the replacement of components such as control modules or sensors. |
| 0x05 | System Programming Failures | This category encompasses faults related to operational software, calibrations, and options. These issues can be resolved by configuring or programming a specific part of the system, such as the control module or sensor. |
| 0x06 | Algorithm-Based Failures | This category covers faults that arise from assessing the plausibility of two or more input parameters or comparing a single parameter to itself over time. |
| 0x07 | Mechanical Failures | This category involves faults detected due to incorrect motion responses related to input or controlled output from the control module. |
| 0x08 | Bus Signal/Message Failures | This category encompasses faults associated with bus hardware and signal integrity. It is also applied when the physical input for a signal is situated in one control module, and another control module diagnoses the circuit or restricts operation due to a reported failure in that circuit. |
| 0x09 | Component Failures | This category comprises faults attributed to component failures, which encompass parametric, performance, assembly, and operating environment failures. |
| 0x0A – 0X0E | ISO/SAE reserved | This range of values is set aside by this section of ISO 15031 for potential future expansion. |
| 0x0F | Vehicle Manufacturer/System Supplier specific | This category is allocated for the exclusive use of vehicle manufacturers and system suppliers. |
The table above outlines the various “DTC Failure Subtypes.” It is imperative that all failure subtypes are designated to be mutually exclusive, meaning that a solitary point of failure should correspond to a single combination of base DTC and failure type byte.
When a detected fault can logically fit into two or more Failure Categories, the category with the lowest number that is relevant to the fault should be selected. There is an exception to this rule: if the lowest number Failure Category requires a value of 0 (hex), in that case, the lowest number Failure Category with a non-zero value should be chosen. Similarly, within a given Failure Category, the lowest number subtype applicable to the fault should be used.
The “General Failure Information” Failure Category should be employed when the fault within that category is unique (and cannot be standardized by introducing a new subtype), or when the detected fault is best described by two or more subtypes within that Failure Category.
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