U0014 Guide to Diagnosing
Medium Speed CAN Communication Bus (+) High
The U0014 OBD-II code signifies an issue with the Medium-Speed CAN Communication Bus (+). This code specifically points to an abnormal high voltage or out-of-range voltage on the positive line of the medium-speed CAN bus. The OBD-II system, which monitors communication among the vehicle's various modules and components, detects this issue.
This code involves the Medium-Speed CAN bus, which is typically used for modules such as body control modules and powertrain control modules. It is triggered when the voltage on the Medium-Speed CAN (+) line deviates from the expected range, leading to disrupted or improper communication between the connected control modules.
Symptoms:
Communication Failures, Dashboard Warning Lights, Loss of Vehicle Functions, Erratic Behavior, Diagnostic Trouble Codes (DTCs)
Possible Causes of U0014 Code :
- Short Circuit: A wiring short to a positive voltage source, causing higher voltage than expected on the CAN bus.
- Damaged Wiring or Connectors: Corrosion, wear, or a broken connection can interrupt the proper functioning of the CAN bus.
- Faulty CAN Bus Module: A malfunctioning control module connected to the bus can cause abnormal voltage levels.
- Faulty Termination Resistor: If the termination resistors on the bus are malfunctioning or improperly connected, it can cause communication issues.
- Electrical Interference: High-voltage spikes or electromagnetic interference could disrupt the CAN signal.
- Loose or Corroded Grounds: Poor grounding or loose connections can lead to irregular voltage levels.
- Faulty Fuses or Relays: If related fuses or relays are damaged, the electrical system might misbehave.
How to Fix it?
Ensure to check for any damaged components and inspect the connector pins for signs of being broken, bent, pushed out, or corroded.
Common Diagnose and Repairs:
Diagnostic Steps:
- Visual Inspection: Inspect the wiring, connectors, and fuses related to the CAN bus for visible damage.
- Scan Tool Diagnostics: Use a scan tool to retrieve additional fault codes and check for other communication problems on the network.
- Check Voltage Levels: Test the voltage on the medium-speed CAN bus (+) to determine if it is within the expected range.
- Check CAN Bus Continuity: Test the resistance and continuity of the wires within the CAN bus network.
- Module Testing: Check if any modules are malfunctioning by isolating them and observing whether the issue persists.
- Grounding Check: Ensure all relevant ground connections are intact and free of corrosion.
Repair:
- Repair any damaged wiring or connectors.
- Replace faulty modules or relays.
- Address electrical interference or grounding issues.
- Replace malfunctioning termination resistors if needed.
- Clear the fault codes after repairs and perform a test drive to ensure the issue is resolved.
