Functional Unit Stored Data Transmission of UDS protocol contains following services-
| Service | Request ServiceID | Response ServiceID | Sub-Function |
|---|---|---|---|
| ClearDTC Service | 0x14 | 0x54 | No |
| ReadDTC Service | 0x19 | 0x59 | Yes |
This Diagnostic service used by the diagnostic tool to clear the DTC(Diagnostic Trouble Code) from the server’s memory.
DTC(Diagnostic Trouble Code) is a fault code stored in memory for faulty control units. There are Number of DTCs for each control unit(Power Train, chassis, Break etc.)DTCs Can be clear in one shot or individual from server’s memory for any control unit through the Request Frame.
Clear Diagnostic UDS Frame Format
This service is used to read DTC from the server’s memory. Sub-function defined by manufacturers decided the data about to read.
Clear Diagnostic UDS Frame Format
In the ’80s, It’s an impossible thing to get the information about malfunctioned unit if a problem is detected in your car and because of this, it was very tough to fix the malfunctioning unit in the car.
But As automobile engineering grows by time, they(ISO, Manufacturer) define the range of generic and manufacturer specific trouble codes for each automobile unit(Power Train, Chassis, body and network unit) and these trouble codes are known as diagnostic trouble codes(DTC).
Every Vehicle Manufacture provides an OBD Connector which is a digital communication medium through which anyone whether he is car owner or repair technician, can read the real-time data of his car and get the information(DTCs) about the malfunctioned unit and repair it accordingly.
Diagnostic Trouble Code Format
DTC code may contain 2 or 3 bytes. Basically, DTC code has DTC high bytes and DTC middle bytes while the last byte is optional
As you can see in the above format DTC has one letter followed by 4 numeric characters i.e total 5 characters.let’s understand the each and every character through the following table-
Example:
Let’s investigate how will look A DTC code 0x0123 to a repair technician?
So it will look P0123 to Technician through which he can understand fault code is generic and related to powertrain family.
https://en.wikipedia.org/wiki/On-board_diagnostics#EOBD_fault_codes