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.
High Speed Controller Area Network (CAN)
The high speed CAN is based on SAE J2284, ISO-11898, and is a serial communication language protocol used to transfer messages (signals) between electronic control modules or nodes. Two or more signals can be sent over one CAN circuit allowing 2 or more electronic modules or nodes to communicate with each other. This communication, or multiplexing, network operates at 500k/sec (kilobytes per second) and allows the electronic modules to share their information messages.
Included in these messages is diagnostic data sent over the CAN+ and CAN- lines to the DLC. The PCM connection to the DLC is typically done with a 2-wire, twisted pair cable used for network interconnection. The diagnostic data such as self-test or PIDs can be accessed with a scan tool. Information on scan tool equipment is described in the DIAGNOSTIC METHODS article, Diagnostic Methods.
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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.