Inductive sensors and AC signals

CORE TEACHING Variable reluctance principle; magnet/coil; generated AC; speed-dependent amplitude/frequency; air gap. PRACTICAL DEMONSTRATIONS AND TESTS Resistance check; AC voltage while spinning/cranking; scope sine waveform; manipulate gap if possible. ADVANCED / SCAN TOOL LAYER Scope healthy vs damaged tone-ring/missing-tooth waveform. KEY DIAGNOSTIC QUESTIONS Should this sensor be supplied or self-generating? Does amplitude rise with speed? Is pattern uniform? MUST-COVER CHECKPOINTS Identify sensor technology; supply/ground if applicable; expected signal type; physical stimulus; scan comparison; scope if time-varying; wiring-to-ECU proof.

Two-wire crank or wheel-speed sensor has no 5 V feed. Is that automatically wrong?

Builds on

Lesson 21: Hall-effect cam and crank sensors

Feeds into

Lesson 23: Pressure sensors — MAP, rail and A/C

1. 18Power, ground and signal — the universal sensor pattern
2. 19Testing a three-wire sensor
3. 20Two-wire temperature and resistive sensors
4. 21Hall-effect cam and crank sensors
5. 22Inductive sensors and AC signals
6. 23Pressure sensors — MAP, rail and A/C
7. 24Temperature sensors in real diagnosis
8. 25Position sensors and plausibility
9. 26Testing actuators: motors, solenoids and valves