Reports traction-motor speed and direction for torque and overspeed control.
SENSOR GUIDE80/86
Identify the circuit first
ONE NAME. DIFFERENT SIGNALS.
Pin count is a clue, not proof. Confirm the exact architecture before resistance testing, applying voltage or judging the waveform.
TYPE 01CONSTRUCTION VARIANT
Two-wire inductive / passive
Confirm wiring, pin count and service information before testing.
The coil generates an AC voltage; it has no external power supply.
Reading the signal
Good waveform
At a steady operating point, motor current and loaded supply are repeatable. A brushed motor may show regular commutation ripple; electronically commutated motors must be assessed with their specific driver and command strategy.
Faulty waveform
Excessive current with little motion can indicate binding or a stalled load. Intermittent current loss can indicate supply, connection or brush problems. Low current can also mean insufficient supply or reduced command. Confirm actual speed, travel, pressure or airflow rather than interpreting current alone.
TYPE-SPECIFIC TESTS
+ Measure resistance only when permitted, then scope both wires while rotating. Amplitude must rise with speed and the air gap matters.
+ Verify the specified supply, ground, bias or termination before judging the signal.
+ Repeat the test through the complete operating range.
EXPECTED
✓ Output matches this construction type
✓ Stable levels and repeatable response
✓ Agreement with related scan data
COMMON FAULTS
— Incorrect test method for the sensor type
— Supply, ground or signal-circuit fault
— Installation, target or calibration concern
TYPE 02CONSTRUCTION VARIANT
Three-wire Hall / active
Confirm wiring, pin count and service information before testing.
A supply and ground power a digital output that switches high and low.
Reading the signal
Good waveform
Logic levels and edge transitions are consistent with the installed circuit. Pulse timing changes in the specified way as the input changes; intended index gaps or encoded features repeat correctly.
Faulty waveform
Missing or extra edges, weak switching levels, intermittent pulse loss or a stuck level can indicate supply, ground, wiring, target or sensor problems. A steady level can be normal when the target is stationary. Decode encoded signals using the correct protocol.
TYPE-SPECIFIC TESTS
+ Verify loaded supply and ground, then scope the signal at the sensor and controller.
+ Verify the specified supply, ground, bias or termination before judging the signal.
+ Repeat the test through the complete operating range.
EXPECTED
✓ Output matches this construction type
✓ Stable levels and repeatable response
✓ Agreement with related scan data
COMMON FAULTS
— Incorrect test method for the sensor type
— Supply, ground or signal-circuit fault
— Installation, target or calibration concern
TYPE 03CONSTRUCTION VARIANT
Two-wire magnetoresistive / active
Confirm wiring, pin count and service information before testing.
The module reads a current-modulated signal from a powered two-wire element.
Reading the signal
Good waveform
At a steady operating point, motor current and loaded supply are repeatable. A brushed motor may show regular commutation ripple; electronically commutated motors must be assessed with their specific driver and command strategy.
Faulty waveform
Excessive current with little motion can indicate binding or a stalled load. Intermittent current loss can indicate supply, connection or brush problems. Low current can also mean insufficient supply or reduced command. Confirm actual speed, travel, pressure or airflow rather than interpreting current alone.
TYPE-SPECIFIC TESTS
+ Use the specified current or voltage conversion method. Do not judge it as an inductive sensor.
+ Verify the specified supply, ground, bias or termination before judging the signal.
+ Repeat the test through the complete operating range.
EXPECTED
✓ Output matches this construction type
✓ Stable levels and repeatable response
✓ Agreement with related scan data
COMMON FAULTS
— Incorrect test method for the sensor type
— Supply, ground or signal-circuit fault
— Installation, target or calibration concern
Correct theory and operation
HOW IT WORKS.
Understand the sensing method, circuit and controller strategy before interpreting data or replacing the component.
01
Measured condition
Reports traction-motor speed and direction for torque and overspeed control.
02
Signal type
Digital or AC speed signal. A Hall, magnetoresistive or inductive element produces pulses whose frequency follows rotational speed.
03
Controller use
The receiving controller checks range, rationality and rate of change against related inputs before setting a fault or substituting a value.
04
Installation matters
Mounting, target condition, air gap, contamination, temperature, shielding or calibration may affect the result even when the circuit is intact.
Common mistakes
AVOID THE FALSE CLUE.
Condemning the sensor before verifying powers, grounds and communication.
Using a generic value instead of vehicle-specific service information.
Checking an unloaded circuit that fails only while operating.
Ignoring mechanical, installation or calibration causes.
Replacing the component without repeating the original test.
COMPLETE TEST SEQUENCE
Identify Hall, magnetoresistive or inductive construction.
Verify supply and ground when required.
Scope the signal while rotating the component.
Compare frequency, amplitude and dropout behavior with related speed inputs.
Repeat the original operating condition and confirm the repair.
DO NOT CONDEMN THE SENSOR
Prove its supply, ground, signal path, physical input and calibration before replacement. Vehicle-specific specifications always win.