Circuit Description
WARNING: This page is about a different car, the 2004 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
The data link connector (DLC) is a standardized 16 cavity connector. Connector design and location is dictated by an industry wide standard, and is required to provide the following:
- Scan tool power battery positive voltage at terminal 16.
- Scan tool power ground at terminal 4.
- Common signal ground at terminal 5.
- Class 2 serial data at terminal 2.
- Keyword serial data at terminal 7.
- GMLAN (+) serial data at terminal 6 w/LY7.
- GMLAN (-) serial data at terminal 14 w/LY7.
The serial data circuits are the means by which the control modules on the vehicle communicate with each other and the scan tool. There are 3 different types of protocols on this vehicle.
- The class 2 serial data
- The control area network (CAN) serial data w/M82
- The keyword serial data
The scan tool will power up with the ignition OFF. Some modules however, will not communicate unless the ignition is ON and the power mode master (PMM) module sends the appropriate power mode message. Refer to Body Control System Description and Operation in Body Control System for operation of the PMM.