UDS_4_传输存储的数据功能单元
一. DTC
》DTC-Diagnostic Trouble Code
J1939-73 DTCFormat
| DTC | |||||
| SPN | FMI | CM | OC | ||
| 8-1位 | 8-1位 | 8-6位 | 5-1位 | 8位 | 7-1位 |
| 字节1 | 字节2 | 字节3 | 字节4 | ||
•ISO14229-1 DTCFormat
•SAE_J2012-DA_DTCFormat_00
| DTC | ||||
| DTC代码值 | DTCStatus | |||
| DTCHighByte | DTCMiddleByte | DTCLowByte | 5-1位 | |
| 字节1 | 字节2 | 字节3 | 字节4 | |
》》故障码(DTC)属性
》代码值
•SAE_J2012-DA_DTCFormat_00
| Hex value | DTCHighByte | |||||||
| Bit7 | Bit6 | Bit5 | Bit4 | Bit3 | Bit2 | Bit1 | Bit0 | |
| First | Second | Third | ||||||
| DTCMiddleByte | |||||||
| Bit7 | Bit6 | Bit5 | Bit4 | Bit3 | Bit2 | Bit1 | Bit0 |
| Fourth and Fifth | |||||||
| HighByte Bit7-6 | Code Categories | System | Appendix |
| 00 | P0xxx – P3xxx | Powertrain | P |
| 01 | C0xxx – C3xxx | Chassis | C |
| 10 | B0xxx – B3xxx | Body | B |
| 11 | U0xxx – U3xxx | Network and Vehicle integration | U |
》DTC状态
| Bit# | 名称 | 描述 |
| 0 | testFailed | 该DTC最近的测试结果为失败 |
| 1 | testFailedThisOperationCycle | 当前操作循环报告该DTC处于故障状态 |
| 2 | pendingDTC | DTC在请求时未经确认 |
| 3 | confirmedDTC | DTC在请求时经过确认 |
| 4 | testNotCompletedSinceLastClear | 自从上一次故障码清除后测试尚未完成 |
| 5 | testFailedSinceLastClear | 自从上一次故障码清除后测试至少失败一次 |
| 6 | testNotCompletedThisOperationCycle | 本操作循环测试未完成 |
| 7 | warningIndicatorRequested | 与该DTC相关的报警指示灯的状态 |
二. 0x14服务
ClearDiagnosticInformation(0x14)服务
》参数-GroupofDTC(DTC组)
| Hex值 | Description | Cvt |
| 0x000000-0x0000FF | Reserved for future legislative requirements | M |
| OEM Specific | Powertrain Group: engine and transmission | U |
| Powertrain DTCs | U | |
| Chassis Group | U | |
| Chassis DTCs | U | |
| Body Group | U | |
| Body DTCs | U | |
| Network Communication Group | U | |
| Network Communication DTCs | U | |
| 0xFFFF00-0xFFFFFE | 低字节为FunctionalGroupIdentifier 参数 | M |
| 0xFFFFFF | All Groups | M |
》 清除故障信息
•DTC
•DTCStatusByte
•DTCSnapshotData
•DTCExtendedData
•其他DTC相关的信息（标志、计数器、计时器等）
》客户端只有通过0x14服务才能清除故障信息
》0x14服务独立于其他任何服务
》请求报文
| A_Data Byte | Parameter Name | Cvt | Byte Value |
| #1 | ClearDiagnosticInformation Request SID | M | 0x14 |
| GroupOfDTC=[ | |||
| #2 | GroupOfDTCHighByte | M | 0x00-0xFF |
| #3 | GroupOfMiddleByte | M |