In 2004, HD implemented the serial data bus (SDB) on all Sportster models. This single wire, digital communications link, provides a means for the Ignition Control Module (ICM), the Turn Signal Module (TSM/TSSM) and Speedometer/Tachometer to intelligently communicate with one another. There is a 4-pin 'port' connector (called a serial data link) to allow external computer connection to the SDB. It is located near the MaxiFuse.

The SDB link allowed the ICM to be reprogrammable because it allowed the factory and the dealer the ability to use one ICM and program it for either 883 engines or 1200 engines. There are updates that can be dealer 'flashed' into the ICM when new parameters will resolve known problems.

The ICM, TSM & Speedo/Tach regularly communicate their current status to one another. When all operating parameters on the serial data line are within specifications, a state of health message is sent between the components.

The SDB is designed upon a standard SAE serial communication protocol callded “J1850”. The digital data is transmitted and received on a single wire at around 10.4 Kbps. This protocol was used thru the 2013 model year. Beginning in 2014, the CANbus, a more capable vehicle communications system, was implemented.

Writing about this subject could fill many pages - but it is recommended that you purchase (along with a factory service manual) the Sportster Electrical Diagnostic Manual for your specific model year if you intend to service your own bike. It is extremely helpful in understanding the electrical intricacies of your bike.

In 2014, HD implemented the Controller Area Network bus (CANbus), sometimes referred to as the HDLAN bus, on all Sportster models. This system uses a two wire, digital communications link, providing a means for the Engine Control Module (ECM), the Body Control Module (BCM), the Speedometer/Tachometer, the right & left handlebar control switches and the Anti-lock Brake System (ABS) to intelligently communicate with one another. There is a 6-pin 'port' connector (called a serial data link) to allow external computer connection to the CANbus. It is located near the MaxiFuse.

The CANbus link allows the ECM/BCM to be reprogrammable for different models and for either 883 engines or 1200 engines. There are updates that can be dealer 'flashed' into the ECM/BCM when new parameters will resolve known problems.

The CANbus components regularly communicate their current status to one another. When all operating parameters on the data line are within specifications, a state of health message is sent between the components.

The CANbus is designed upon a standard SAE serial communication protocol. The digital data is transmitted and received using a differential signal on two wires at around 500Kbps.

Writing about this subject could fill many pages - but it is recommended that you purchase (along with a factory service manual) the Sportster Electrical Diagnostic Manual for your specific model year if you intend to service your own bike. It is extremely helpful in understanding the electrical intricacies of your bike.