Code U0006 on the 2021 Lincoln Aviator indicates that CAN Bus B circuit voltage is higher than normal operating range. This condition prevents proper communication between body and comfort system modules on the medium-speed CAN network.
Understanding Bus B High Condition
When CAN Bus B reads high, the voltage on CAN-H and/or CAN-L is elevated above specification. Normal CAN differential voltage varies between approximately 0V and 2V during message transmission. A high condition means something is pulling the voltage up, typically a short to a power source.
Affected Systems
CAN Bus B typically handles the Aviator's body electronics - power liftgate, door modules, seat memory, ambient lighting, and portions of the SYNC system. With U0006 present, these features may malfunction or become completely inoperative as modules cannot communicate properly.
Diagnostic Path
Look for shorts to power in the Bus B wiring. Check areas where body harnesses pass near power distribution - behind the dash, in door panels near courtesy lights, and near any aftermarket accessories that may have been incorrectly wired. Measure actual voltage on CAN-H and CAN-L to confirm the high condition.
Repair Approach
Trace the short to power source by sectionally disconnecting harness segments or modules while monitoring bus voltage. Once voltage returns to normal, you've isolated the problem area. Repair the wiring damage and ensure no power sources can contact the CAN lines.