Important Preliminary Checks Before Starting
- Perform the «Diagnostic System Check - Vehicle»(ref-300843-S03018657462008101600000) before using the Symptom Tables in order to verify that all of the following are true: There are no DTCs set. The control modules can communicate via the serial data link.
- Review the description and operation in order to familiarize yourself with the system functions. Refer to «Data Link Communications Description and Operation»(ref-300869-S17861651672008101600000) .
Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .
UART Data line
UART-Based communication systems have a master of the serial data line and remote transceivers. The master controls the message traffic on the serial data line by polling all of the remotes (control modules). The master then waits for the proper response.
- The UART serial data line: The UART serial data line allows the following components to communicate data with a scan tool: The electronic brake control module (EBCM) The transaxle control module (TCM) The inflatable restraint sensing and diagnostic module (SDM) The immobilizer control module The anti-theft module
- The UART serial data line allows a scan tool to communicate with these modules for diagnosis and testing.
Keyword 2000 Data Line
The Keyword protocols utilize a single wire bi-directional data line between the module and the scan tool. The message structure is a request and response arrangement. Keyword 2000 is used for scan tool diagnostics only. The modules do not exchange data on these systems.
The keyword 2000 serial data line
- The keyword 2000 serial data line allows the following to communicate with the scan tool: The engine control module.
- The keyword 2000 serial data line allows a scan tool to communicate with this module for diagnosis and testing.