Scheme 1
Scheme 2
DIAGNOSTIC CODE INDEX
| DTC | Description |
|---|---|
| DTC U0100-U0299 (DTC U0101) | Lost Communication With Transmission Control Module |
DIAGNOSTIC CODE INDEX
Circuit Description
Modules that are connected to the shared communication circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have pre-recorded information about what messages are needed to be exchanged on the serial data circuits for each virtual network. The messages are usually supervised and some periodic messages are used by the receiver module as an availability indication of the transmitter module.
DTC Descriptors
This diagnostic procedure supports the following DTC
DTC U0101 Lost Communication With Transmission Control Module (TCM)
Conditions for Running the DTCs
- The ignition is ON.
- The DTC U0101 diagnostic runs continuously when the above condition is met.
Conditions for Setting the DTC
The engine control module (ECM) cannot communicate with the TCM.
Action Taken When the DTC Sets
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
- 1: When the ECM stores a DTC U0101, a DTC U2105 simultaneously sets in the TCM. Performing the diagnostic procedures in DTC U2105 will repair DTC U0101.
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Use the scan tool in order to clear the DTCs. Turn OFF the ignition for 30 seconds. Start the engine. Use the scan tool and check for DTCs. Is DTC U0101 present? | Go to Diagnostic Trouble Code (DTC) List - Vehicle | Go to Step 2 |
| 2 | Does the scan tool communicate with the engine control module (ECM) and transmission control module (TCM)? | Go to Diagnostic System Check - Vehicle | Go to Scan Tool Does Not Communicate with CAN Device |
Important Preliminary Checks Before Starting
- Perform the «Diagnostic System Check - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) before using the Symptom Tables in order to verify that all of the following are true: There are no DTCs set. The control modules can communicate via the serial data link.
- Review the description and operation in order to familiarize yourself with the system functions. Refer to «Data Link Communications Description and Operation»(/chevrolet/aveo/i-2006-2012/remont/communication-devices/#data-communication-system) .
Visual/Physical Inspection
- Inspect for aftermarket devices which could affect the operation of the system. Refer to «Checking Aftermarket Accessories»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-inline-harness-connector-end-views-diagnosis__checking-aftermarket-accessories) .
- Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom
- «Scan Tool Does Not Power Up»(/chevrolet/aveo/i-2006-2012/remont/communication-devices/#data-communication-system)
- «Scan Tool Does Not Communicate with CAN Device»(/chevrolet/aveo/i-2006-2012/remont/communication-devices/#data-communication-system)
The data link connector (DLC) provides operating power for the scan tool at terminal 16. The ground for the scan tool is provided at terminal 4. The 16- pin DLC provides the serial data signals at terminals 7 (engine control module (ECM), transmission control module (TCM), immobilizer serial data), 8 (theft deterrent serial data), 12 (ABS serial data), and 13 (SIR serial data). The scan tool will power up with the ignition OFF. The ignition must be ON in order for the scan tool to communicate with a control module.
The numbers below refer to the step numbers on the diagnostic table.
- 1: Fuse F11 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.
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Test the battery positive voltage circuit of the data link connector (DLC) for an open or short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 5 | Go to Step 2 |
| 2 | Test the ground circuit or the DLC for an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 5 | Go to Step 3 |
| 3 | Inspect for poor connections at the DLC ground terminals and the DLC power terminals at the DLC. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 5 | Go to Step 4 |
| 4 | The scan tool may be malfunctioning. Refer to the scan tool user guide. Did you obtain a properly operating scan tool? | Go to Step 5 | |
| 5 | Does the scan tool power up? | Go to Diagnostic System Check - Vehicle | Go to Step 1 |
The provisions for communicating with the engine control module (ECM), electronic brake control module (EBCM), SIR module, immobilizer module, and the theft deterrent module are located in the data link connector (DLC). The DLC is located under the instrument panel (I/P). The 16 pin DLC provides the serial data signals at terminals 7 (ECM, TCM, immobilizer serial data), 8 (theft deterrent serial data), 12 (ABS serial data), and 13 (SIR serial data). The DLC is used to link a scan tool to the ECM, EBCM, SIR, immobilizer, and theft control modules serial data stream. Some common uses of the scan tool are listed below
- Identifying the stored diagnostic trouble codes (DTCs)
- Reading the serial data stream
- Clearing the DTCs
- Storing the Freeze Frame data
Diagnostic Aids
Some scan tools may require an external power supply. Ensure the scan tool is correctly connected to the power feed.
Ensure that the correct application (model year, carline, VIN code) has been selected on the scan tool. If communications are still not established, try the scan tool on another vehicle in order to ensure that the scan tool or the connecting cables are not the cause of the malfunction. Always try the scan tool on a vehicle that uses the same DLC terminal for serial data communication.
Any circuitry that is suspect to an intermittent complaint should be thoroughly inspected for the following
- Backed-out terminals
- Improper mating of terminals
- Broken electrical connector locks
- Improperly formed or damaged terminals
- Faulty terminal-to-wiring connections
- Physical damage to the wiring harness
- A broken conductor inside the wire insulation
- Corrosion of the electrical connections, the splices, or the terminals
The numbers below refer to the step numbers on the diagnostic table.
- 3: This step checks whether the scan tool can communicate with other control modules on the vehicle. If the scan tool can communicate with one of the other modules then the DLC connector, the shared circuits, and the scan tool are OK.
- 4: This step checks whether the ECM is receiving ignition positive voltage from the fuse F16 when the ignition is ON. The ECM cannot provide serial data without ignition positive voltage.
- 7: This step checks for a high resistance or an open/short in the ECM serial data circuit.
- 8: This step checks the ECM DLC Diagnostic circuit high resistance or open/short. This could cause the ECM not to communicate.
- 9: This step checks to see if the EBCM is not communicating with the scan tool.
- 14: This step checks to see if the SIR system is not communicating with the scan tool.
- 19: This step checks to see if the theft deterrent-immobilizer system is not communicating with the scan tool.
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Have you performed the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Does the scan tool power up? | Go to Step 3 | Go to Scan Tool Does Not Power Up |
| 3 | Does the scan tool communicate with the engine control module (ECM)? | Go to Step 9 | Go to Step 4 |
| 4 | With the ignition OFF: Disconnect the ECM connector. Turn ON the ignition. Test the ECM battery positive (B+) and/or ignition voltage circuits with a test lamp connected to ground. Does the test lamp illuminate for all circuits? | Go to Step 5 | Go to Step 24 |
| 5 | With the ECM still disconnected, test the ECM ground circuits with a test lamp connected to B+. Does the test lamp illuminate for all ground circuits? | Go to Step 6 | Go to Step 24 |
| 6 | Reconnect the ECM connector. Connect the scan tool. Turn ON the ignition, with the engine OFF. Does the scan tool display serial data? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 7 |
| 7 | Test the serial data circuit for an open, high resistance, or a short circuit. Refer to Circuit Testing . Did you find and correct the condition? | Go to Step 29 | Go to Step 8 |
| 8 | Test the data link connector (DLC) diagnostic circuit for an open, high resistance or a short circuit. Refer to Circuit Testing . Did you find and correct the condition? | Go to Step 29 | Go to Step 25 |
| 9 | Does the scan tool communicate with the electronic brake control module (EBCM)? | Go to Step 14 | Go to Step 10 |
| 10 | Test the EBCM battery positive (B+) and/or ignition voltage circuits with a test lamp to ground. Does the test lamp illuminate for all circuits? | Go to Step 11 | Go to Step 24 |
| 11 | Test the EBCM ground circuits with a test lamp connected to B+. Does the test lamp illuminate for all circuits? | Go to Step 12 | Go to Step 24 |
| 12 | Test the EBCM serial data circuit for an open, high resistance, or short circuit. Refer to Circuit Testing . Did you find and correct the condition? | Go to Step 29 | Go to Step 13 |
| 13 | Inspect the EBCM connectors. Refer to Wiring Repairs or Connector Repairs . Did you find and correct the condition? | Go to Step 29 | Go to Step 26 |
| 14 | Does the scan tool communicate with the SIR module? | Go to Step 19 | Go to Step 15 |
| 15 | Test the SIR module battery positive (B+) and/or ignition voltage circuits with a test lamp to ground. Does the test lamp illuminate for all circuits? | Go to Step 16 | Go to Step 24 |
| 16 | Test the SIR module ground circuits with a test lamp connected to B+. Does the test lamp illuminate for all circuits? | Go to Step 17 | Go to Step 24 |
| 17 | Test the SIR serial data circuit for an open, high resistance, or short circuit. Refer to Circuit Testing . Did you find and correct the condition? | Go to Step 29 | Go to Step 18 |
| 18 | Inspect the SIR module connectors. Refer to Wiring Repairs or Connector Repairs . Did you find and correct the condition? | Go to Step 29 | Go to Step 27 |
| 19 | Does the scan tool communicate with the theft deterrent module? | Go to Step 29 | Go to Step 20 |
| 20 | Test the theft deterrent module battery positive voltage B+ and/or ignition voltage circuits with a test lamp to ground. Does the test lamp illuminate for all circuits? | Go to Step 21 | Go to Step 24 |
| 21 | Test the theft deterrent module ground circuits with a test lamp connected to B+. Does the test lamp illuminate for all circuits? | Go to Step 22 | Go to Step 24 |
| 22 | Test the theft deterrent serial data circuit for an open, high resistance, or short circuit. Refer to Circuit Testing . Did you find and correct the condition? | Go to Step 29 | Go to Step 23 |
| 23 | Inspect the theft deterrent module connectors. Refer to Wiring Repairs or Connector Repairs . Did you find and correct the condition? | Go to Step 29 | Go to Step 28 |
| 24 | Repair the circuit as necessary. Refer to Wiring Repairs or Connector Repairs . Is the action complete? | Go to Step 29 | |
| 25 | Replace the ECM. Is the action complete? | Go to Step 29 | |
| 26 | Replace the EBCM. Refer to Brake Pressure Modulator Valve Assembly Replacement . Is the action complete? | Go to Step 29 | |
| 27 | Replace the SIR module. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement (North America) or Inflatable Restraint Sensing and Diagnostic Module Replacement (Except North America) . Is the action complete? | Go to Step 29 | |
| 28 | Replace the theft deterrent module. Is the action complete? | Go to Step 29 | |
| 29 | Operate the system in order to verify the repair. Is the action complete? | System OK | Go to Step 3 |
Regulations and agreements among the automobile manufacturers have resulted in the data link connector (DLC). This connector must be used for the scan tool and programming access to all communications systems used for the purposes on the vehicle. The connector must have the following
- A 16-pin connector configuration to which all scan tools connect
- Scan tool battery power always available at pin 16
- Scan tool ground always available at pin 4
- A clean signal ground always available at pin 5
The rest of the pins are available for serial data communications to the vehicle system. The serial data circuits are the means by which the microprocesor-controlled modules in the vehicle communicate with each other and the scan tool. There are 2 different types of protocols on this vehicle
- The Universal Asynchronous Receiver Transmitter (UART)
- Keyword 2000 Data line
The scan tool accesses the following module data lines
- The electronic brake control module (EBCM) (UART)
- The engine control module (ECM) (Keyword 2000)
- The transmission control module (TCM) (UART)
- The inflatable restraint sensing and diagnostic module (SDM) (UART)
- The immobilizer control module (UART)
- The anti-theft module (UART)
UART Data line
UART-Based communication systems have a master of the serial data line and remote transceivers. The master controls the message traffic on the serial data line by polling all of the remotes (control modules). The master then waits for the proper response.
- The UART serial data line: The UART serial data line allows the following components to communicate data with a scan tool: The electronic brake control module (EBCM) The transaxle control module (TCM) The inflatable restraint sensing and diagnostic module (SDM) The immobilizer control module The anti-theft module
- The UART serial data line allows a scan tool to communicate with these modules for diagnosis and testing.
Keyword 2000 Data Line
The Keyword protocols utilize a single wire bi-directional data line between the module and the scan tool. The message structure is a request and response arrangement. Keyword 2000 is used for scan tool diagnostics only. The modules do not exchange data on these systems.
The keyword 2000 serial data line
- The keyword 2000 serial data line allows the following to communicate with the scan tool: The engine control module.
- The keyword 2000 serial data line allows a scan tool to communicate with this module for diagnosis and testing.
See also:
• Diagnostic Trouble Code (DTC) List - Vehicle
• Diagnostic System Check - Vehicle
• Checking Aftermarket Accessories
• Testing for Intermittent Conditions and Poor Connections
• Circuit Testing
• Wiring Repairs
• Connector Repairs
• Brake Pressure Modulator Valve Assembly Replacement
• Inflatable Restraint Sensing and Diagnostic Module Replacement (North America)
• DTC U0100-U0299 (DTC U0101)