Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
CAN Communication Signal
CAN communication system is a serial communication system for transmitting multiple data items (values from sensors, control data and control signals) as ON-OFF digital signals through communication lines.
This system uses two lines (CAN High and CAN Low) for the communication circuit so as to maintain high reliability even when used for high-speed serial communication.
Serial communication is established as shown below with 2.5 V as the reference level for both CAN High signal (1) and CAN Low signal (2). The range of CAN High signal is from 2.5 V to about 3.5 V and that of CAN Low signal is from 2.5 V to about 1.5 V. When both are at 2.5 V, signal is judged as OFF. When CAN High signal is 3.5 V and CAN Low signal is 1.5 V (that is, when the difference between High voltage and Low voltage is more than about 2 V), signal is judged as ON. For this reason, a feature of CAN communication signal is that the signal waveform between CAN High and CAN Low signals is symmetrical with respect to 2.5 V level. CAN communication fails when the symmetrical signal form collapses.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.