Test Description
WARNING: This page is about a different car, the 2000 Cadillac Catera. However, it is still accessible from the selected car via links, so may be relevant.
The number(s) below refer to the step number(s) on the diagnostic table. No information has been left out.
- 2. A DTC U2100 set in either the ECM, TCM or EBTCM may have caused U2105 to set. You must diagnose and clear DTC U2100 to determine if it is the cause of U2105 setting
- 3. If the Engine Control Module (ECM) loses power, it will cause other module(s) to set Lost Communication DTCs
- 5. The malfunction is due to an open in the CAN Bus serial data circuit or an open in the module
- 8. Because of the malfunction, The ECM may have set CAN Bus DTCs for those modules that it was monitoring
- 10. The Transmission Control Module (TCM) and Electronic Brake and Traction Control Module (EBTCM) may have set other CAN Bus DTCs because of the original malfunction. You must clear the DTCs from these modules to avoid future misdiagnosis
DTC U2105 LOST COMM WITH ENGINE CONTROL SYSTEM
| Step | Action | Value(s) | Yes | No |
| 1 | Was the Data Link Communications Diagnostic System Check performed? | -- | Go to Step 2 | Diagnostic System Check - Data Link Communications |
| 2 | Was DTC U2100 recorded as a history or current DTC in the ECM, TCM or EBTCM? | -- | Go to DTC U2100 CAN-BUS Communication Malfunction testing in this article | Go to Step 3 |
| 3 | 1. Inspect and test the ECM battery feed circuit for proper voltage. 2. Inspect and test all ECM Ignition feed circuits for proper voltage. 3. Inspect and test all ECM ground circuits. Refer to ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article Did you find and correct the condition? |
-- | Go to Step 8 | Go to Step 4 |
| 4 | Inspect for poor connections/terminal tension at the CAN Bus serial data circuit(s) of the module that set DTC U2105. Refer to TESTING FOR INTERMITTENTS & POOR CONNECTIONS Did you find and correct the condition? |
-- | Go to Step 8 | Go to Step 5 |
| 5 | Test the CAN Bus serial data circuit(s) for an open between the module that set DTC U2105 and the ECM.. Did you find and correct the condition? |
-- | Go to Step 8 | Go to Step 6 |
| 6 | Inspect for poor connections/terminal tension at the CAN Bus serial data circuit(s) of the ECM. Refer to TESTING FOR INTERMITTENTS & POOR CONNECTIONS Did you find and correct the condition? |
-- | Go to Step 8 | Go to Step 7 |
| 7 | Replace the ECM. Refer to POWERTRAIN CONTROL MODULE
Replacement Did you complete the replacement? |
-- | Go to Step 10 | -- |
| 8 | 1. Install a scan tool. 2. Turn the ignition switch to the ON position, leaving the engine off. 3. Select the Display DTCs function in Engine Controls. Does the scan tool display any DTCs other than the following? * U2103 * U2104 * U2106 * U2108 |
-- | Go to DTC INDEX | Go to Step 9 |
| 9 | Clear the DTCs using the scan tool. Did you complete the action? |
-- | Go to Step 10 | -- |
| 10 | Select the Display DTCs function for the module(s) which set DTC U2105. Does the scan tool display any DTCs other than the following? * U2103 * U2104 * U2105 |
-- | Go to DTC INDEX | Go to Step 11 |
| 11 | 1. Clear the DTCs using the scan tool. 2. Continue diagnosing or clearing the DTCs until all the modules have been diagnosed and all the DTCs have been cleared. Did you complete the action? |
-- | System OK | -- |