For 1990-2009 cars only
| • | RPO JE3 -- The scan tool is connected to the EBCM (electronic brake control module) via the UART (universal asynchronous receiver transmitter) format at pin 12. |
| • | RPO JE5 -- The scan tool is connected to the EBCM and the ECM (engine control module) via the CAN (controlled area network) format at pins 7 and 15. |
Universal Asynchronous Transmitter Receiver (UART) Data Line
Circuit 799 exists pin 12 of the DLC, and is a dedicated communication link between the EBCM and the scan tool. When a communication failure exists with the EBCM, this circuit should be checked. This UART circuit can exist alone, or in conjunction with class 2 serial data communication information, depending on the vehicle, functions/RPOs.
