Computers and Control Systems: Application and ID

On Board Diagnostic (OBD) technical data

Memory
- Temporary memory and permanent memory. If the engine control module is disconnected from the Battery Positive Voltage (B+) supply, the readiness code and learning values will be erased. Any malfunctions stored in DTC memory are not erased.

Data output
- Rapid data transfer
- Additional malfunction indication by Malfunction Indicator Lamp (MIL) lighting up

ECM identification
- VAG 1551 Scan Tool (ST), connecting and selecting "Engine Electronics" address word 01. [1][2]Scan Tool Connecting and Initial Checks

ECM functions
- The Motronic ECM -J220- performs different OBD functions, carried out with the ignition switched on or with the engine running. Following are the conditions required to carry out each of the specific functions.

Address words:
Address word 00: Automatic Test Sequence Ignition switched on -or- Engine running at idle
Address word 01: Engine Electronics Ignition switched on -or- Engine running at idle
Address word 33: OBD II (generic scan tool) Ignition switched on -or- Engine running at idle