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.
Circuit/System Description
There are 2 ignition 1 voltage circuits supplied to the engine control module (ECM). The first ignition 1 voltage circuit is provided by the powertrain relay, through the ETC/ECM fuse, located in the underhood fuse block. This ignition 1 voltage circuit supplies power to all the internal ECM circuits associated with the throttle actuator control (TAC) operation, and to both TAC motor control circuits to the throttle body. The ignition main relay provides the second ignition 1 voltage circuit to the ECM, through the ECM IGN fuse located in the underhood fuse block. This ignition 1 voltage provides power to all internal ECM circuits, except those associated with TAC operation. The ECM continuously monitors both ignition 1 voltage circuits. If the ECM detects a voltage level difference between the two circuits, DTC P1682 will set.
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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.