U0007 Guide to Diagnosing
High Speed CAN Communication Bus (-) Low
The U0007 OBD-II code indicates an issue with the high-speed CAN (Controller Area Network) communication bus. Specifically, it points to a low voltage in the CAN bus (-) signal, which disrupts communication among various vehicle modules. Here's a detailed explanation:
Affected Systems:
- Engine Control Module (ECM)
- Transmission Control Module (TCM)
- Anti-lock Braking System (ABS) module
- Other connected systems
Symptoms:
Illuminated Check Engine Light (CEL), Communication Issues, Malfunctioning Systems, Intermittent or Complete System Failures, Erratic Vehicle Behavior
Possible Causes of U0007 Code :
- Damaged Wiring or Connectors
- Corrosion, wear, or physical damage to the CAN bus (-) wire.
- Poor connections or loose terminals at the CAN bus connectors.
- Short Circuit: A short to ground or power in the CAN bus (-) wire.
- Faulty Control Module: A malfunctioning module may send incorrect signals or disrupt network communication.
- Electrical Interference: External electrical noise interfering with CAN bus signals.
- Low Battery Voltage: Insufficient power supply can impair CAN communication.
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:
- Check for Other Codes: Other related CAN communication codes may provide more context.
- Inspect Wiring and Connectors: Look for damaged, corroded, or loose connections in the CAN (-) line.
- Measure Voltage and Resistance:
- Verify the voltage and resistance levels of the CAN (-) wire with a multimeter.
- Typical resistance for the CAN bus is 60 ohms (using termination resistors).
- Test Modules: Isolate potentially faulty modules by disconnecting them one by one and checking communication.
- Repair or Replace Components:
- Repair damaged wiring or connectors.
- Replace faulty control modules or sensors.
- Clear and Test: Clear the code with a scanner and perform a test drive to ensure the issue is resolved.
