Hybrid & EV / RES

MOTOR RESOLVER / POSITION SENSOR

Reports electric-machine rotor angle for inverter commutation and torque control.

SENSOR GUIDE79/86

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

Resolver

Confirm wiring, pin count and service information before testing.

Excitation produces sine and cosine return channels representing rotor angle.

Reading the signal

Good waveform

Position feedback follows commanded or measured movement consistently, with the specified relationship between channels. A resolver requires correct excitation and a consistent sine/cosine relationship; other encoders must be interpreted according to their interface.

Faulty waveform

Dropouts, a dead region, disagreement between channels or feedback that fails to follow motion can indicate circuit, target, calibration or mechanical problems. A command without motion is not proof of a feedback-sensor failure.

TYPE-SPECIFIC TESTS

+ Use approved isolated equipment and verify excitation, sine, cosine and learned offset together.

+ 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

Hall or magnetic encoder

Confirm wiring, pin count and service information before testing.

Digital magnetic channels report rotor sectors or absolute position.

Reading the signal

Good waveform

Position feedback follows commanded or measured movement consistently, with the specified relationship between channels. A resolver requires correct excitation and a consistent sine/cosine relationship; other encoders must be interpreted according to their interface.

Faulty waveform

Dropouts, a dead region, disagreement between channels or feedback that fails to follow motion can indicate circuit, target, calibration or mechanical problems. A command without motion is not proof of a feedback-sensor failure.

TYPE-SPECIFIC TESTS

+ Verify supply and synchronized channel sequence while rotating under approved conditions.

+ 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

Optical encoder

Confirm wiring, pin count and service information before testing.

A coded optical disc produces incremental or absolute position data.

Reading the signal

Good waveform

Position feedback follows commanded or measured movement consistently, with the specified relationship between channels. A resolver requires correct excitation and a consistent sine/cosine relationship; other encoders must be interpreted according to their interface.

Faulty waveform

Dropouts, a dead region, disagreement between channels or feedback that fails to follow motion can indicate circuit, target, calibration or mechanical problems. A command without motion is not proof of a feedback-sensor failure.

TYPE-SPECIFIC TESTS

+ Inspect contamination and alignment; compare channel timing and index pulse.

+ 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 electric-machine rotor angle for inverter commutation and torque control.

02

Signal type

Multi-channel AC position signal. An excited rotary transformer returns sine and cosine signals whose relationship identifies rotor angle.

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.

COMPLETE TEST SEQUENCE

  1. Use the high-voltage disable procedure before connector access.
  2. Inspect resolver wiring and shielding.
  3. Scope excitation, sine and cosine together with appropriate isolated equipment.
  4. Verify learned offset and motor position data.
  5. 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.

SENSOR LIBRARYReturn to all sensors→

Diagnostic details

Construction & type-specific testing

Identify the installed design before testing. Construction, signal format and redundant channels are separate attributes; use only the procedure for the actual component.

Resolver

An excited transformer-like winding system produces sine/cosine signals related to rotor angle.

Operating principle

  • An excited transformer-like winding system produces sine/cosine signals related to rotor angle.

Circuit identification

Application-specific; see wiring below

Wiring

  • Excitation and differential sine/cosine pairs; shields are not signal returns.

Expected readings

  • Sine/cosine channels preserve the specified relationship to excitation and rotor position.

Multimeter testing

  • Use approved differential equipment to compare excitation and both return channels under the OEM safe test conditions.

Oscilloscope setup

  • Identify the output interface and approved test points before connecting. Set the range, coupling and probes for that circuit.

Oscilloscope testing

  • Use approved differential equipment to compare excitation and both return channels under the OEM safe test conditions.
  • High-voltage drive systems require trained personnel and the OEM isolation procedure. Do not rotate or energize a traction motor casually; it can generate voltage.

Waveform interpretation

Sine/cosine channels preserve the specified relationship to excitation and rotor position. No universal known-good waveform is specified for this design.

Common failures

  • Connection, supply or signal-path faults where applicable
  • Damage, installation error or loss of calibration appropriate to this design

Diagnostic tips

  • High-voltage drive systems require trained personnel and the OEM isolation procedure. Do not rotate or energize a traction motor casually; it can generate voltage.
  • Construction, output format and number of redundant channels are separate attributes.
Magnetic Rotor Position Sensor

A magnetic target is measured by Hall or magnetoresistive electronics.

Operating principle

  • A magnetic target is measured by Hall or magnetoresistive electronics.

Circuit identification

Application-specific; see wiring below

Wiring

  • Powered channels with design-specific analog or digital output.

Expected readings

  • Valid position data and the specified channel sequence.

Multimeter testing

  • Check module data, supply and target alignment using the approved low-voltage test points.

Oscilloscope setup

  • Identify the output interface and approved test points before connecting. Set the range, coupling and probes for that circuit.

Oscilloscope testing

  • Check module data, supply and target alignment using the approved low-voltage test points.
  • High-voltage drive systems require trained personnel and the OEM isolation procedure. Do not rotate or energize a traction motor casually; it can generate voltage.

Waveform interpretation

Valid position data and the specified channel sequence. No universal known-good waveform is specified for this design.

Common failures

  • Connection, supply or signal-path faults where applicable
  • Damage, installation error or loss of calibration appropriate to this design

Diagnostic tips

  • High-voltage drive systems require trained personnel and the OEM isolation procedure. Do not rotate or energize a traction motor casually; it can generate voltage.
  • Construction, output format and number of redundant channels are separate attributes.
Contactless Inductive Rotor Position Sensor

Excited coils measure a conductive rotor target without a magnetic encoder.

Operating principle

  • Excited coils measure a conductive rotor target without a magnetic encoder.

Circuit identification

Application-specific; see wiring below

Wiring

  • Powered sensor electronics; interface depends on the assembly.

Expected readings

  • Repeatable rotor angle with valid synchronization and calibration.

Multimeter testing

  • Compare reported rotor position with the specified calibration and signal procedure.

Oscilloscope setup

  • Identify the output interface and approved test points before connecting. Set the range, coupling and probes for that circuit.

Oscilloscope testing

  • Compare reported rotor position with the specified calibration and signal procedure.
  • High-voltage drive systems require trained personnel and the OEM isolation procedure. Do not rotate or energize a traction motor casually; it can generate voltage.

Waveform interpretation

Repeatable rotor angle with valid synchronization and calibration. No universal known-good waveform is specified for this design.

Common failures

  • Connection, supply or signal-path faults where applicable
  • Damage, installation error or loss of calibration appropriate to this design

Diagnostic tips

  • High-voltage drive systems require trained personnel and the OEM isolation procedure. Do not rotate or energize a traction motor casually; it can generate voltage.
  • Construction, output format and number of redundant channels are separate attributes.