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.
Description & Operation
Vehicle is not equipped with a Body Control Module (BCM). Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. In addition to this, node alive messages are transmitted by each module on the class 2 serial data circuit about once every 2 seconds. When the module detects the class 2 serial data circuit shorted, the setting of all other class 2 serial communication DTCs is inhibited and a U1300, U1301, or a U1305 DTC will set.
The class 2 serial data line allows communication between modules and scan tool. Modules on the class 2 serial data line are:
- Electronic Brake Control Module (EBCM).
- Inflatable Restraint Sensing and Diagnostic Module (SDM).
- Powertrain Control Module (PCM).
- Radio (IRC).
- Vehicle Immobilizer Module (VIM).
- Vehicle Theft Deterrent Module (VTD).
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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.