Test Description
WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. 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 ground 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 DTCs from these modules to avoid future misdiagnosis.
DTC U1001-U1254
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Data Link Connector (DLC) Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems |
|||
| 1 | Test the battery positive voltage and ignition B+ circuits of the module that is not communicating for an open or a short to ground. Refer to the following:
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 connector. 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 B+ 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 | Replace the module which is not communicating. Refer to Control Module References for replacement, setup and programming for the appropriate repair instructions. Did you complete the replacement? |
Go to Step 9 | - |
| 7 |
|
Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | 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 Diagnostic System Check - Vehicle in Vehicle DTC Information | Go to Step 10 |
| 10 |
|
System OK | - |