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.