OBD-II code U0063 indicates a short circuit condition on Vehicle Communication Bus D, a specific high-speed data network used for module-to-module communication. This electrical fault disrupts data flow, often causing multiple control modules to lose contact with each other or enter a fail-safe mode. The issue is typically rooted in wiring harness damage or connector corrosion rather than internal module failure.
Physical wear where the bus wires rub against the chassis or engine components is the most common cause, creating a direct short to ground or power.
Water intrusion into network junctions or module connectors can bridge pins, causing a short circuit on the bus lines.
Recently installed electronics (alarms, stereos, trackers) tapped into the wrong wires or poorly spliced connections can short the communication bus.
An internal fault within a specific node on Bus D can pull the entire network down, though this is less frequent than external wiring issues.
Animals nesting in the engine bay or dashboard may chew through insulation, exposing conductors and causing shorts.
While possible, an internal short within the PCM itself is statistically rare and should only be considered after all wiring and other modules are ruled out.
No, in the vast majority of cases, this code is caused by damaged wiring or a connector issue, not a failed PCM. Replacing the computer without verifying the harness first is rarely the correct fix.
It is generally unsafe to drive, as the short can disable critical systems like braking assistance, steering control, or engine management, potentially leading to a sudden loss of vehicle control.
Because Bus D connects multiple modules, a single short circuit prevents them from communicating, causing each module to log a 'loss of communication' fault with every other module on the network.
No, clearing the code will only temporarily turn off the warning light; the short circuit is a physical hardware fault that will cause the code to return immediately once the system cycles.