High Speed CAN Communication Bus (+) Open

Description

The CAN High wire is open, disrupting high-speed bus communication. CAN H carries the dominant high signal.

Symptoms

• Multiple modules offline
• Warning lights illuminated
• Systems inoperative
• No scan tool communication on some modules

Common Causes

• Broken CAN H wire
• Corroded CAN H terminal
• Damaged CAN bus connector
• Wiring harness damage

Diagnostic Steps

1. Measure voltage on CAN H (should be ~2.5V idle, ~3.5V dominant)
2. Check continuity of CAN H wire
3. Inspect CAN bus connectors
4. Locate break using voltage drop test

Repair Notes

Locate and repair the open in the CAN H wire. Check all splice points.

Related Codes

Other Network Codes

U0003 on Other Vehicles

Common Questions

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