Scheme 1
Scheme 2
Scheme 3
Scheme 4
Test Description
The numbers below refer to the step numbers on the diagnostic table.
1. A DTC U1001 - U1254 Lost Communications with XXX with a history status may indicate the cause of U1000 or U1255.
2. The modules not communicating are the likely cause of U1000 or U1255. The modules that are available on the class 2 serial data circuit are listed in the Circuit Description.
6. The module which was not communicating due to a poor connection to the class 2 serial data circuit may have set DTC U1001 - U1254 Lost Communications with XXX for those modules that it was monitoring.
9. The modules which can communicate indicate the module which cannot communicate. You must clear the serial data communication DTCs from these modules to avoid future misdiagnosis.
12. If all modules are communicating, the module which set U1000 or U1255 may have done so due to some other condition.
14. The module which set U1000 or U1255 is the likely cause of the malfunction.
Scheme 5
Scheme 6
The number below refers to the step number on the diagnostic table.
6. The module which was not communicating on the class 2 serial data circuit may have set the Loss of Communication DTCs for the modules it was monitoring.
Scheme 7
The numbers below refer to the step numbers on the diagnostic table.
1. The CIG fuse supplies power to terminal 16 of the DLC.
4. The battery positive voltage and ground circuits of the DLC are functioning properly. The malfunction must be due to the scan tool.
Scheme 8
The numbers below refer to the step numbers 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 and U1301 may be retrieved with a history status. These DTCs are not the cause of the present condition.
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.
7. Data link connector terminals 2 and 5 provide the connection to the Class 2 serial data circuit and the signal ground circuit respectively.
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.
11. If communication can be established, the malfunction is not in the BCM or the wiring from the DLC to the BCM.
12. This test attempts to establish communication with the Radio.
13. This test attempts to establish communication with the DRR.
14. This test attempts to establish communication with the VCIM.
15. This test attempts to establish communication with the PCM.
16. This test attempts to establish communication with the IPC.
17. This test attempts to establish communication with the SDM.
18. This test attempts to establish communication with the EBCM.
19. This test analyzes the condition of the wiring and connectors in the Class 2 serial data circuit of the BCM.
20. This test analyzes the condition of the wiring and connectors in the Class 2 serial data circuit of the Radio.
21. This test analyzes the condition of the wiring and connectors in the Class 2 serial data circuit between the Radio and the DRR module.
22. This test analyzes the condition of the wiring and connectors in the Class 2 serial data circuit between the Radio and the VCIM module.
23. This test analyzes the condition of the wiring and connectors in the Class 2 serial data circuit of the PCM.
24. This test analyzes the condition of the wiring and connectors in the Class 2 serial data circuit of the IPC.
25. This test analyzes the condition of the wiring and connectors in the Class 2 serial data circuit of the SDM.
26. This test analyzes the condition of the wiring and connectors in the Class 2 serial data circuit of the EBCM.
36. If there are no current DTCs that begin with a U, the communication malfunction has been repaired.
38. The interruption of the Class 2 serial data circuit may have prevented the diagnosis of the customer complaint.
