What is the Cause of CAN Bus Failure?

[Nevaeh]

Here are the reasons for failures in the CAN bus system: 1. Faults caused by the vehicle's power system. The operating voltage of automotive electronic control modules is generally between 10.5-15.0V. If the working voltage provided by the vehicle's power system is abnormal, it can cause certain electronic control modules to malfunction temporarily, leading to communication issues in the entire vehicle CAN bus system. 2. Link faults in the vehicle CAN bus system. Short circuits, open circuits, or physical changes in the communication lines that cause signal attenuation or distortion can result in multiple electronic control units malfunctioning, rendering the CAN bus system inoperative. 3. Node faults in the vehicle CAN bus system. Nodes are the electronic control modules in the vehicle CAN bus system, and node faults refer to failures in these modules. This includes software faults, such as defects or conflicts in the transmission protocol or software programs, which can cause chaos or complete failure in the vehicle CAN bus system communication.

[LaJanelle]

Last time I encountered a Passat with CAN bus issues, it was a real headache. Simply put, this thing is the central nervous system of a car, connecting modules like the engine control unit, ABS, and instrument cluster. If warning lights on the dashboard start flashing randomly, windows stop responding, or even the engine suddenly stalls, there's a good chance the bus has failed. Common problems include wiring chewed by rodents, water ingress causing connector oxidation, or modules malfunctioning and conflicting with each other. Once after heavy rain, we towed in a Tiguan where the door control module got flooded and short-circuited the entire bus. My advice: if the dashboard shows random faults, first try disconnecting the battery to reboot. If that doesn't work, immediately visit a professional shop to read trouble codes with a diagnostic tool—never randomly unplug connectors yourself.