Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 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.
2. 3)  - The DTC U1300 and U1301 may be retrieved with a history status. These DTCs are not the cause of the present condition.
3. 6)  - A State of Health DTC with a history status may be present along with a U1000 with a current status. This indicates that the malfunction occurred when the ignition was on.
4. 7)  - Data link connector terminals 2 and 5 provide the connection to the Class 2 serial data circuit and the signal ground circuit respectively.
5. 10)  - An open in the Class 2 serial data circuit between the DLC and the body control module (BCM) will prevent the scan tool from communicating with any module. This condition will not set a DTC.
6. 11)  - If communication can be established, the malfunction is not in the BCM or the wiring from the DLC to the BCM.
7. 12)  - This test attempts to establish communication with the Radio.
8. 13)  - This test attempts to establish communication with the PCM.
9. 14)  - This test attempts to establish communication with the IPC.
10. 15)  - This test attempts to establish communication with the SDM.
11. 16)  - This test attempts to establish communication with the EBCM.
12. 17)  - This test analyzes the condition of the wiring and connectors in the Class 2 serial data circuit of the BCM.
13. 18)  - This test analyzes the condition of the wiring and connectors in the Class 2 serial data circuit of the Radio.
14. 19)  - This test analyzes the condition of the wiring and connectors in the Class 2 serial data circuit of the PCM.
15. 20)  - This test analyzes the condition of the wiring and connectors in the Class 2 serial data circuit of the IPC.
16. 21)  - This test analyzes the condition of the wiring and connectors in the Class 2 serial data circuit of the SDM.
17. 23)  - This test analyzes the condition of the wiring and connectors in the Class 2 serial data circuit of the EBCM.
18. 24)  - If there are no current DTCs that begin with a U, the communication malfunction has been repaired.
19. 25)  - The interruption of the Class 2 serial data circuit may have prevented the diagnosis of the customer complaint.
Fig 1: Scan Tool Does Not Communicate with Class 2 Device (Steps 1-3)
Courtesy of GENERAL MOTORS CORP.
Fig 2: Scan Tool Does Not Communicate with Class 2 Device (Steps 4-10)
Courtesy of GENERAL MOTORS CORP.
Fig 3: Scan Tool Does Not Communicate with Class 2 Device (Steps 11-14)
Courtesy of GENERAL MOTORS CORP.
Fig 4: Scan Tool Does Not Communicate with Class 2 Device (Steps 15-18)
Courtesy of GENERAL MOTORS CORP.
Fig 5: Scan Tool Does Not Communicate with Class 2 Device (Steps 19-20)
Courtesy of GENERAL MOTORS CORP.
Fig 6: Scan Tool Does Not Communicate with Class 2 Device (Steps 21-26)
Courtesy of GENERAL MOTORS CORP.
Fig 7: Scan Tool Does Not Communicate with Class 2 Device (Steps 27-34)
Courtesy of GENERAL MOTORS CORP.