How to Resolve U0140 Loss of Communication with Body Control Module?
2 Answers
Solution for U0140 loss of communication with body control module: It is necessary to check whether the computer board connector is oxidized and whether the throttle pedal connector has poor contact. Use the elimination method to resolve this fault. After troubleshooting, the fault code needs to be cleared. Below is additional information: 1. Introduction to the vehicle fault self-diagnosis system: Generally, vehicles equipped with microprocessor control units have a fault self-diagnosis system. It can be used to automatically check and monitor the working status of various parts of the vehicle's transmission system and control system. When a fault occurs in the vehicle, the fault indicator light on the dashboard will flash to warn the owner that there may be a problem. Pressing a button will display the fault code on the dashboard. At the same time, this fault signal will be stored in the memory. Even if the ignition switch is turned off, the fault is resolved, and the fault indicator light goes out, the fault signal will remain in the memory for maintenance personnel to determine the location of the vehicle's fault. After troubleshooting, disconnecting the ECU power for 30 seconds will clear the fault code. 2. Function: Detecting faults. The level signal input to the microprocessor has a certain range under normal conditions. If a signal outside this range is input, the ECU will diagnose that the signal system is in an abnormal state. For example, the engine coolant temperature signal system stipulates that under normal conditions, the sensor voltage is 0.08-4.8V. Any value outside this range will be diagnosed as abnormal. Fault classification: When the microcomputer is working normally, it detects abnormal input signals through diagnostic programs, and then classifies the detection results into minor faults that do not cause obstacles, faults that cause functional degradation, and major faults. The faults are classified by importance and pre-programmed. When the microcomputer itself fails, major faults are classified through WDT.
As someone who frequently works on car repairs, the U0140 code indicates a loss of communication with the Body Control Module (BCM), which is a tricky issue. First, I would unplug the BCM connector to check for any looseness or corrosion—oxidized copper pins can block signal transmission. Next, I’d use a multimeter to test the module’s power supply voltage; it should normally be around 12V. If it’s below 10V, I’d need to inspect the alternator or battery. Fuses should also be checked one by one, especially those related to the body—replace any that are blown. For damaged or short-circuited wiring, I’d wrap them with insulating tape, as older cars are particularly prone to this issue. If all else fails, I’d have to reprogram the module software using a diagnostic tool or replace the BCM entirely, which is best done at a 4S shop. After repairs, I’d test the headlights and door locks to avoid driving blind at night. Delaying fixes could even disable the anti-theft system, so it’s crucial to address this promptly—safety first.
