Information Bus: Description and Operation

There is one data line that can be accessed with a scan tool. The 461 circuit data line is the ECM Data Line. It allows the Electronic Control Module and Electronic Brake Control Module (EBCM) (if equipped) to communicate by transmitting data through the ORN (461) wire.
A scan tool can be connected to the ALDL Connector, this allows the scan tool to communicate with the ECM Data Line. System operations can then be monitored for diagnostic purpose.