Scan Tool Does Not Communicate with Keyword Data Line

SCAN TOOL DOES NOT COMMUNICATE WITH KEYWORD DATA LINE

CIRCUIT DESCRIPTION
Modules connected to the serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. Connecting a scan tool to the data link connector (DLC) allows communication with the modules for diagnostic purposes.

TEST DESCRIPTION

Step 1 - Step 8:

The numbers below refer to the step numbers on the diagnostic table.
3. A partial malfunction in the serial data circuit uses a different procedure from a total malfunction of the serial data circuit. The following modules communicate on the serial data circuit.
- Communication interface module (OnStar(R))
- Electronic brake control module (EBCM)
- Inflatable restraint sensing and diagnostic module (SDM)
- Instrument panel cluster (IPC)
- Radio
5. DLC terminals 2 and 5 provide the connection to the serial data circuit and the signal ground circuit respectively.
7. A poor connection at splice pack S232 will cause this condition but will not set a DTC.
8. An open in the serial data circuit between the DLC and splice pack S232 will prevent the scan tool from communicating with any module on the network. This condition will not set a DTC.