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U0101 Hummer Code - Lost Communication With Transmission Control Module

- Code Popularity: 6,873 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
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What are the Possible Causes of the DTC U0101 Hummer?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Faulty Transmission Control Module (TCM)
  • TCM harness is open or shorted
  • TCM circuit poor electrical connection
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How to Fix the DTC U0101 Hummer?

Review the 'Possible Causes' mentioned above and visually examine the corresponding wiring harness and connectors. Ensure to check for any damaged components and inspect the connector pins for signs of being broken, bent, pushed out, or corroded.

Code Tech Notes

There is a factory service bulletin for the 2008-2009 HUMMER H2:
2008-2009 HUMMER H2 Factory Service Bulletin OBDII Code U0101

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U0101 Hummer code, it typically requires 1.0 hour of labor. The specific diagnosis time and labor rates at auto repair shops can differ based on factors such as the location, make and model of the vehicle, and even the engine type. It is common for most auto repair shops to charge between $75 and $150 per hour.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

Code U0101 Hummer Description

Modules connected to the high-speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised, and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module.
The serial data circuit is how the devices in the vehicle communicate with each other. Once the scan tool is connected to the serial data circuit through the Data Link Connector (DLC), the scan tool can be used to monitor each device for diagnostic purposes and to check for Diagnostic Trouble Codes (DTC). When the ignition switch is in RUN, each device communicating on the serial data circuit sends a state of health message to ensure that the device is operating correctly. When a device stops communicating on the serial data circuit, for example, if the device loses power or ground, the state of health message, it normally sends on the serial data circuit disappears. Other devices on the serial data circuit, which expect to receive that state of health message, detect its absence; those devices, in turn, set a DTC associated with the loss of the state of health of the non-communicating device. The DTC is unique to the device which is not communicating, and one or more devices may set the same code. A loss of serial data communications DTC does not represent a failure of the devices that contain the stored code.

OBDII Code U0101 Hummer - Lost Communication With Transmission Control Module  - AutoCodes.com
U0101 Hummer Code - Lost Communication With Transmission Control Module

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