CAN High and CAN Low Explained
CAN High and CAN Low are the two wires used in the CAN Bus network. Understanding how they work together is essential for diagnosing communication faults and testing modern vehicle systems correctly.
Understand How CAN High and CAN Low Work Together
CAN communication is based on a differential signal, meaning both wires work together to transmit data.
Instead of using a single voltage signal, CAN uses the difference between the two lines to ensure stable communication.
Test CAN High and CAN Low Correctly
Proper testing of CAN lines helps determine whether the network is functioning correctly or affected by wiring or module faults.
Check Resistance (Ignition OFF)
Measure between CAN High and CAN Low. A healthy network should show around 60 ohms.
Measure Voltage (Ignition ON)
CAN High ~2.5–3.5V and CAN Low ~2.5–1.5V during communication.
Check for Shorts
Test for short to ground, power or between CAN lines.
Verify Signal Stability
Signals should fluctuate smoothly, not remain fixed or drop to zero.
Recognize Common Faults on CAN Lines
Problems on CAN High or CAN Low can disrupt the entire network, causing communication failure.
Identifying typical faults helps speed up diagnosis and repair.
Understand CAN Signals and Diagnose Faster
Learn how CAN High and CAN Low behave, how to test signals correctly and diagnose communication faults with confidence.