Test Description
WARNING: This page is about a different car, the 2004 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
The numbers below refer to the step numbers on the diagnostic table.
- 1: A module which loses power during an ignition cycle will cause other modules to set Lost Communication DTCs.
- 2: A module which loses power during an ignition cycle will cause other modules to set Lost Communication DTCs.
- 3: The malfunction is due to an open in the class 2 serial data circuit or an open in the module.
- 7: The module which was not communicating may have set Lost Communication DTCs for those modules that it was monitoring.
- 9: The modules which can communicate indicate the module which cannot communicate. You must clear the DTC from these modules to avoid future misdiagnosis.
DTC U1001-U1254
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Test the battery positive voltage circuits and the ignition voltage circuits of the module that is not communicating for an open or a short to ground. Refer to Control Module References
in Body Control System for the applicable schematic. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 9 | Go to Step 2 |
| 2 |
|
Go to Step 9 | Go to Step 3 |
| 3 |
|
Go to Step 7 | Go to Step 4 |
| 4 | Test the class 2 serial data circuit of the module that is not communicating for an open between the module and the star connectors. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 7 | Go to Step 5 |
| 5 | Inspect for poor connections at the battery positive voltage circuits, the ignition voltage circuits, the ground circuits, and the class 2 serial data circuit of the module that is not communicating. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 7 | Go to Step 6 |
| 6 |
IMPORTANT:
Perform the set up procedure for module if required. Replace the module which is not communicating. Refer to Control Module References
in Body Control System.Did you complete the replacement? |
Go to Step 9 | - |
| 7 |
|
Go to Control Module References in Body Control System for the applicable Diagnostic System Check | Go to Step 8 |
| 8 | Use the scan tool in order to clear the DTCs. Did you complete the action? |
Go to Step 9 | - |
| 9 | Select the Display DTCs function for the modules which had the Lost Communication with XXX DTC set. Does the scan tool display any DTCs which do not begin with a"U"? |
Go to Control Module References in Body Control System for the applicable Diagnostic System Check | Go to Step 10 |
| 10 |
|
System OK | - |