What does code U0107 mean?

Code U0107 stands for Lost Communication with Throttle Actuator (TAC) Module.

Older vehicles use a mechanical throttle linkage to connect the gas pedal to the throttle. Modern vehicles, however, do not have a throttle linkage. Instead they have an electronic throttle body. This eliminates the binding problems caused by the mechanical linkage. It also improves fuel economy and emissions.

Throttle body

The electronic throttle body usually consists of the following components:

  • A motor that opens and closes the throttle
  • Two throttle position sensors (TP)
  • One or more accelerator position sensors (APP)
  • An electronic throttle actuator (TAC) module (this is the computer that controls the throttle body)

As the name implies, the TP sensors are used to determine the throttle plate angle. The APP sensors are used to calculator throttle accelerator pedal position. This information is used by the TAC to determine control of the throttle motor.

The TAC communicates with the other modules throughout the vehicle, via the Controller Area Network (CAN) bus. The CAN bus consists of two lines: CAN High and CAN Low. CAN high communicates at a higher rate of 500k bits/second, whereas CAN Low communicates at 125k bits/second. The ends of the CAN bus contain two terminating resistors.

Code U0107 indicates the TAC module is not receiving or transmitting messages on the CAN bus.

U0107 symptoms

Common causes for U0107

Code U0107 is typically caused by one of the following:

  • A dead battery
  • A faulty TAC module
  • A problem with TAC module circuit
  • A problem with the CAN bus
Get it diagnosed by a professional

How to diagnose and repair U0107

Perform a preliminary inspection

Sometimes U0107 can pop up intermittently, or it can result from a dead battery. This is especially true if the code is a history code and not current. Clear the code and see if it returns. If it does, the next step is to perform a visual inspection. A trained eye can check for issues such as broken wires and loose connections. If a problem is found, the issue should be repaired and the code cleared. If nothing is discovered, check for technical service bulletins (TSBs). TSBs are recommended diagnostic and repair procedures put out by the vehicle manufacturer. Finding a related TSB can greatly reduce diagnostic time.

Check the battery

Like any other module, the TAC needs proper battery voltage to operate. Check the battery and charging system and repair as needed. Then, clear the DTCs and see if they return.

Check for other DTCs

Additional diagnostic trouble codes (DTCs) may indicate problems elsewhere that are affecting TAC module operation. For example, multiple communication DTCs may indicate a problem with the CAN network. Any additional DTCs should be addressed prior to diagnosing U0107.

In the case where multiple communication DTCs are stored, diagnosis will shift to the CAN bus. Like any other electrical circuit, the bus can be checked for problems such as opens and shorts. Bus testing typically starts at the data link connector, either with a digital multimeter (DMM) or a breakout box. Pin 6 of the datalink connector is CAN High, whereas pin 14 is CAN low. If a problem is detected, further testing and repair of the CAN bus can be completed as needed.

Check for a faulty control module

If U0107 is the only DTC stored, the TAC module itself should be checked. The easiest was to start this process is by attempting to communicate with the TAC using a diagnostic scan tool. Once connected to the vehicle, the tool acts like just another module on the network. It can be used to address the TAC module. If the module does not respond, there is a problem with it.

Before condemning the module, it's important to check its circuit. Like any other electronic device, the TAC module must have proper power and ground. This can be checked using a DMM.

If the module's circuit it good, yet it still won't communicate, it is likely faulty. Before replacing the module, however, its software should be checked. Often times a module can be reprogrammed instead of replaced.

Other diagnostic codes related to U0107

All the 'U' codes are network communication codes. Codes U0100 to U0300 are lost communication with XX module codes.

Code U0107 technical details

When this DTC is set, the electronic throttle control system will usually be forced to operate in reduced power mode.

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