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.
Discrete Ignition Signals
Those modules that have discrete ignition signal inputs also remain in state dictated by last valid BCM message received on serial data circuits. They check state of their discrete ignition input to determine current valid state. If discrete ignition input is active, battery voltage, modules will fail-safe to run power mode. If discrete ignition input is not active (open or 0 voltage), modules will fail-safe to OFF (awake). In this state modules are constantly checking for a change status message on serial data circuits and can respond to both local inputs and serial data inputs from other modules on vehicle.
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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.