Keyword Serial Data Line
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 keyword protocols utilize a single wire bi-directional data line between the modules and the scan tool. The message structure is a request and response arrangement. The keyword serial data line is used for scan tool diagnostics only. The modules do not exchange data on this circuit.
The modules on the keyword serial data line can include the following:
- Engine control module (ECM)
- Transmission control module (TCM)
- Headlamp assembly-LF w/TR7
- Headlamp assembly-RF w/TR7