Scan Tool Does Not Communicate With Class 2 Device

Diagnostic Chart (Part 1 Of 4):

Diagnostic Chart (Part 2 Of 4):

Diagnostic Chart (Part 3 Of 4):

Diagnostic Chart (Part 4 Of 4):

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 DLC allows communication with the modules for diagnostic purposes

DIAGNOSTIC AIDS
The engine will not start when there is a total malfunction of the class 2 serial data circuit while the engine is not running.

TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.
2. 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.
3. The DTC U1300, U1301, and U1305 may be retrieved with a history status. These DTCs are not the cause of the present condition.
4. A State of Health DTC with a history status may Lie present along with a U1000 or a U1255 with a current status. This indicates that the malfunction occurred when the ignition was on.
5. The head up display (HUD), the memory seat module (MSM), and the remote function actuator (RFA) are not monitored by other modules. When one of these modules is not communicating, diagnose the malfunction using the specified procedure.
6. Data link connector terminals 2 and 5 provide the connection to the class 2 serial data circuit and the signal ground circuit respectively.
8. An open in the class 2 serial data circuit between the DLC and connector C201 (w/o UV6) or splice S202 (w/ UV6) will prevent the scan tool from communicating with any module. This condition will not set a DTC.
9. The class 2 serial data circuit is shorted to voltage or to ground. The condition may be due to the wiring or due to a malfunction in one of the modules. When you test the wiring for a short, make sure there is not a module connected to the wire being tested.
10. If communication can be established, the malfunction is in the rear integration module (RIM); the compact disc changer (CDX), if equipped with U1S; the sensing and diagnostic module (SDM); or the wiring between these devices
12. If communication can be established, the malfunction is in the remote function actuator (RFA), or the wiring between the RFA and the RIM.
14. If communication can be established, the malfunction is in the electronic brake control module (EBCM); the memory seat module (MSM), if equipped with A45; or the wiring between these devices and the RFA. If communication cannot be established, the malfunction is in the powertrain control module (PCM), or the wiring between the PCM and the EBCM.
17. If communication can be established, the malfunction is in the driver door module (DDM), the vehicle theft deterrent (VTD), or the wiring between the PCM and the flex wiring harness.
18. If communication cannot be established, the malfunction is in the wiring between the VTD and connector C215.
20. If communication can be established, the malfunction is in the climate control panel (CCP), if equipped with C67; the integrated radio chassis (IRC); the instrument panel cluster (IPC); or the flex wiring harness. When the malfunction is in the flex wiring harness, the flex wiring harness must be replaced. If communication cannot be established, the malfunction is in the dash integration module (DIM); the head up display (HUD), if equipped with UV6; the instrument panel integration module (IPM), if equipped with CJ2; or the wiring connected to the DLC at terminal 2.
24. Since the short is not in the wiring harness the malfunction is due to one of the modules.
28. If there are no current DTCs that begin with a U, the communication malfunction has been repaired.
29. The communication malfunction may have prevented diagnosis of the customer complaint.

For a description of the RPO Code(s) shown in this article refer to the RPO Code List found at Vehicle/Application ID Application and ID