| Pin No. | Function | Description | | :--- | :--- | :--- | | | CAN High (J1939) | Communication Bus High | | 13 | CAN Low (J1939) | Communication Bus Low | | 20 | Tachometer Output | Engine RPM Signal to Dash | | 25 | Check Engine Lamp | Ground trigger for MIL light | | 40 | Vehicle Speed Sensor | Input from Transmission |