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.

Diagnostic Aids

The engine will not start when there is a total loss of class 2 serial data communication while the ignition is OFF. The following conditions will cause a total loss of class 2 serial data communication:

* A class 2 serial data circuit shorted to ground.
* A class 2 serial data circuit shorted to voltage.
* An internal condition within a module or connector on the class 2 serial data circuit, that causes a short to voltage or ground to the class 2 serial data circuit.

Test Description

Step 1 - Step 10:

Step 11 - Step 17:

Step 18 - Step 20:

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:

* The body control module (BCM)
* The electronic brake control module (EBCM)
* The inflatable restraint sensing and diagnostic module (SDM)
* The instrument panel cluster (IPC)
* The powertrain control module (PCM)
* The radio
* The rear seat entertainment (RSE) assembly
* The transfer case shift control module (TCSCM)
* The vehicle communication interface module (VCIM)

4. The following DTCs may be retrieved with a history status, but are not the cause of the present condition.

* U1300
* U1301
* U1305

7. A state of health DTC with a history status may be present along with a U1000 or U1255 code having a current status. This indicates that the malfunction occurred when the ignition was ON.
8. Data link connector terminals 2 and 5 provide the connection to the class 2 serial data circuit and the signal ground circuit respectively.
18. If there are no current DTCs that begin with a "U", the communication malfunction has been repaired.
19. The communication malfunction may have prevented diagnosis of the customer complaint.