P0512 indicates a malfunction in the electrical circuit responsible for signaling the starter motor to engage. The Powertrain Control Module detects an unexpected voltage or signal pattern when the ignition is activated. This prevents the engine from cranking or causes irregular starter operation.
Mechanical wear inside the switch often prevents the starter signal from being sent to the control module.
The relay contacts may burn out or the coil may fail to close the circuit required for cranking.
A power surge or short circuit can interrupt voltage supply to the starter request line.
Corrosion or breaks in the harness prevent signal transmission between components.
Internal failure within the starter assembly can reflect back as a circuit error.
Internal circuitry monitoring the signal may fail, though this is statistically rare.
The definition is universal; the diagnostics are engine-specific. Open your vehicle for the codes documented for it:
No, this code usually points to the ignition switch, relay, or wiring, not the PCM.
No, the vehicle may not start or could stall unexpectedly.
Sometimes, as anti-theft systems interrupt the starter request circuit.
The PCM monitors the circuit, but internal failure is statistically rare compared to switches and relays.