Scan Tool Does Not Communicate with Class 2 Device

SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE

CIRCUIT DESCRIPTION
Modules connected to the class 2 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 class 2 serial data circuit uses a different procedure from a total malfunction of the class 2 serial data circuit. The following modules communicate on the class 2 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 class 2 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 class 2 serial data circuit between the DLC and splice pack S232 will prevent the scan tool from communicating with any module on the class 2 network. This condition will not set a DTC.