What is indicated by a weak signal from a reluctance type speed sensor?

A weak signal from a reluctance type speed sensor typically indicates that the sensor is not generating sufficient voltage due to an issue with the sensor's magnetic circuit. The correct interpretation is that the sensor coil might be shorted, leading to a diminished output signal. In this scenario, the electrical resistance is significantly reduced, which prevents the sensor from properly generating the electromagnetic field required for accurate speed signal production.

Reluctance type speed sensors work by detecting changes in magnetic fields. If the coil is shorted, it can defeat the sensor's ability to function correctly, resulting in a weak or nonexistent signal.

The condition of the air gap is also crucial, as an air gap that is less than specified could cause a too-strong signal or interference, but it would not solely account for a weak signal. A sensor coil being open would result in no signal at all, and a loose ground connection would more likely lead to fluctuating or inconsistent signals rather than a consistently weak signal. Thus, recognizing a shorted coil as a cause of weak signals helps in diagnosing and potentially fixing the sensor issue effectively.