The U0101 code is typically the same as a U0100 code, but some makes and models will send the U0101 code if there’s a specific problem with the TCM, while the U0100 code may be more general and applies to all communication issues with the ECM, PCM, and TCM.
Additionally, only some models have the U0101 code, while every vehicle make and model since 1996 will send a U0100 code.
What Does Code p061b Mean?
Error code U0101 means that the TCM, or transmission control module, is unable to communicate with other control modules on the vehicle.
Typically, the vehicle will send this code if the PCM (powertrain control module), which monitors the CAN (controller area network), hasn’t received any messages within a specific amount of time, as a well-functioning TCM will send messages regularly.
There are a number of other computers (referred to as modules) on board a vehicle. The TCM communicates with these modules over the controller area network (CAN) bus. CAN is a two-wire bus, consisting of the CAN High and CAN Low lines.
There are two terminating resistors, one at each end of the CAN bus. These are needed to terminate communication signals which flow both ways.
Code U0101 indicates the TCM is not receiving or transmitting messages on the CAN bus.
Potential Causes of a u0101 Code
Code U0101 is typically caused by one of the following:
- A dead battery
- A faulty TCM
- A problem with the TCM circuit
- A problem with the CAN bus
- Problems with the data bus
u0101 Code Symptoms
- An illuminated check engine (MIL) light
- Transmission performance issues
- Problems with the instrument cluster PRNDL display
- The vehicle stays in one gear or in limp mode
How to Fix u0101
Diagnosing and fixing the U0101 code can be a complex process. It often involves running a full diagnostic scan to check for any other DTCs (Diagnostic Trouble Codes) and to exclude other potential causes.
Here are the essential steps to diagnose and fix the U0101 code:
Perform a full diagnostic scan:
Run a comprehensive scan using a professional OBD-II scanner to identify other potential issues and rule out any unrelated trouble codes
Check the grounds:
Inspect all ground connections related to the TCM (Transmission Control Module) for any loose, corroded, or damaged connections. Ensure all grounds are secure and clean.
Inspect the wiring harness
Carefully examine the wiring harness associated with the TCM for any visible damage, such as frayed wires or exposed insulation. Refer to a wiring diagram to locate the TCM module and find all the ground points.
Inspect the TCM connector:
Carefully examine the TCM connector for any signs of damage, corrosion, or bent pins. Ensure the connector is securely fastened and making proper contact.
Perform power and ground voltage checks:
Use a digital voltmeter to verify that there is adequate power and ground voltage at the TCM module. Check for proper voltage levels in accordance with the manufacturer’s specifications.
Probe the TCM connector:
Use an oscilloscope or multimeter to probe the TCM connector and diagnose any communication issues on the CAN bus. Look for abnormalities or fluctuations in the signal.
Consider professional assistanceConsider professional assistance:
If all diagnostic steps have been performed without success and communication is still not possible, it may indicate a faulty TCM. In such cases, it is recommended to seek professional assistance for TCM replacement and programming.
By following these diagnostic steps, you can effectively diagnose and fix the U0101 code, ensuring the proper functioning of the transmission system.
How Much Does It Cost to Fix a 0101 Code?
Fixing a U0101 code, which indicates a “lost communication with Transmission Control Module (TCM),” typically costs between $200 and $1,000 depending on the cause of the issue, whether it’s a simple wiring repair or requires replacing the TCM itself, and the labor costs associated with your vehicle and location.