U0144 – Data bus: body control module (8CM) D- no communication

Reinier

By Reinier (Contact Me)
Last Updated 2020-08-12
Automobile Repair Shop Owner

Trouble CodeFault LocationProbable Cause
U0144 Data bus: body control module (8CM) D- no communication

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What Does Code U0144 Mean?

OBD II fault code U0144 is a generic trouble code that is defined as “Lost Communication with Body Control Module “D”, and is set when the PCM (Powertrain Control Module) detects a break in communication between itself and the BCM (Body Control Module). In some cases, this code will also set if a break is detected between the PCM and other control modules that communicate with the PCM via the BCM over one or more serial communications networks.

Modern vehicles can contain several dozen control modules that collectively, control, monitor, and manage every aspect of the vehicle’s operation. In practice though, some modules are dedicated to specific functions, such as the BCM that is limited to controlling functions that include but are not limited to, climate control, power window/seat adjustment, interior lighting, and others. Which specific functions are controlled by the BCM on any given application depends on the vehicle, and that particular models’ trim level and fitted equipment.

Nonetheless, the PCM on almost all vehicles act as a sort of clearinghouse for all communications, including communications to and from the BCM from other control modules. We need not delve into the complexities of modern serial communications systems here, beyond saying that many of the communications that Body Control Modules both transmit and receive are shared by various other control modules, including the PCM to verify the overall integrity of all serial communications systems.

One particular example of why stable communication is required between the PCM and the BCM involves climate control. Since the operation of the climate control system has a direct bearing on engine performance, the PCM needs to know not only the status of the climate control system but also the various settings of the system so it (the PCM) can make appropriate adjustments to, for instance, the idling speed to prevent the engine from stalling during idling.

There are many other possible examples, but the point is that for the PCM to control and monitor the myriad functions that keep modern vehicles operating safely and reliably, it needs to have uninterrupted access to all communications between all control modules over all active communications networks. Thus, if a break in communication between the PCM and the BCM occurs, the PCM will recognize that it cannot control, monitor, manage some of its own, specific functions, and/or monitor the functions of other control modules, and it will set a fault code as a result. Note that depending on the application, warning lights may not be illuminated immediately, or may not be illuminated at all.

Where is the U0144 sensor located?

This image shows the typical functions that body control modules perform on most vehicles. Note though that while the actual location of the body control module varies greatly between manufacturers, these control modules are typically located under the dashboard, or inside the center console. Other possible locations include placement under the front or rear seats, or in a few cases, in the engine compartment close to the firewall.

What are the common causes of code U0144?

Common causes of code U0144 could include one or more of the following-

  • Internal corrosion as the result of water ingress into the BCM
  • Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors almost anywhere in the CAN bus or other serial communications system
  • Corrupted BCM software
  • Excessive heat, moisture, or vibration
  • Incorrect jump-starting procedures
  • Abnormally high or low system voltages
  • Charging system failure
  • Battery failure

What are the symptoms of code U0144?

Possible symptoms of code U0144 are many and varied but largely depend on the vehicle and the exact nature of the problem. Therefore, since this list of possible symptoms is neither exhaustive nor complete, it is recommended that reference be made to reliable service information for more details on possible symptoms that may or may not apply to any given vehicle. Nonetheless, common symptoms could include one or more of the following-

  • Stored trouble code
  • In some cases, multiple other codes relating to serial communications issues may be present along with U0144
  • Several warning lights may be illuminated
  • Interior lighting may not work
  • Vehicle may not start, or the vehicle may be immobilized completely
  • On vehicles with keyless entry systems, it may not be possible to gain entry into the vehicle as doors will remain locked
  • Security, anti-theft, or central locking system may work erratically, or may not work at all
  • ABS, Stability Control, and Traction Control systems may not be available
  • Airbags might not deploy, and other SRS features may not be available
  • Instruments may behave erratically, and/or some instruments may not work at all
  • Power seats and windows may not work

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