Class 2 Serial Data Link
The following modules use the class 2 serial data link to communicate
with each other:
| • | The body control module (BCM) |
| • | The digital radio receiver (DRR) |
| • | The electronic brake control module (EBCM) |
| • | The inflatable restraint sensing and diagnostic module (SDM) |
| • | The powertrain control module (PCM) |
| • | The vehicle theft deterrent (VTD) |
The class 2 serial data link also allows a scan tool to communicate with
the above modules for diagnostic and testing purposes.
The class 2 serial data link on this vehicle is configured in a star
pattern. There is no redundant path for the serial data to flow through. If a class 2
serial data circuit develops an open condition, the module connected by that circuit
will not be able to communicate.
Data Link Connector (DLC)
The data link connector (DLC) allows a scan tool to communicate with
the class 2 modules. The DLC is a standardized 16 cavity connector located
below the instrument panel and close to the steering column. Connector design and
location is dictated by an industry wide standard, and it is required to provide the
following:
| • | Scan tool power battery positive voltage at terminal 16. |
| • | Scan tool power ground at terminal 4. |
| • | Class 2 serial data signal at terminal 2. |
| • | Common signal ground at terminal 5. |
Refer to
Computer/Integrating Systems Connector End Views
Diagnostic Trouble Codes (DTCs)
Each control module connected to the class 2 serial data circuit monitors
serial data communications during normal vehicle operation. Operating information
and commands are exchanged among the modules. In addition, node alive messages are
transmitted by each module on the class 2 serial data circuit about once every
2 seconds. If a module does not receive a node alive message when expected,
a DTC will set. If a module detects that the class 2 serial data circuit is
shorted, the setting of all other class 2 serial communication DTCs is inhibited,
and DTC U1300, U1301, or U1305 will set.
