Energy conversion
A reversible motor or solenoid moves the latch when the body controller briefly reverses polarity.
Body electrical / LOCK
DOOR LOCK ACTUATOR
A reversible motor or solenoid moves the latch when the body controller briefly reverses polarity.
OUTPUT GUIDE10/11
Correct theory and operation
HOW IT
WORKS.
Understand the component, its circuit and the controller's strategy before interpreting the waveform or beginning disassembly.
Driver strategy
Timed H-bridge polarity reversal. The exact high-side, low-side, H-bridge or smart-module arrangement must be confirmed from the wiring diagram.
Mechanical operation
A body controller briefly reverses polarity through an H-bridge to run a DC motor in lock or unlock direction. Gears, a rack or linkage move the latch and then current is removed.
Closed-loop behavior
The pulse is intentionally short to prevent overheating. Mechanical load shapes current, while latch switches or door-ajar inputs may provide separate state feedback.
Normal response
Battery polarity reverses by direction Brief current rise then completion drop Similar response across doors
Common mistakes
AVOID THE
FALSE CLUE.
- Testing with the connector unplugged when the fault only appears under load.
- Using a generic voltage value instead of the vehicle-specific specification.
- Skipping power, ground and reference checks before condemning the component.
- Moving the harness or clearing codes before capturing the original evidence.
- Replacing a part without repeating the test.
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.
COMPLETE TEST SEQUENCE
- Verify mechanical latch movement.
- Command lock and unlock on both wires.
- Check voltage drop during the pulse.
- Compare current with a good door.
- Inspect hinge-area wiring.
Verify controller request, loaded voltage, current signature and mechanical or hydraulic response as separate evidence.
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.
Door Lock Actuator
COMPLETE TEST SEQUENCE
- 1. Verify mechanical latch movement.
- 2. Command lock and unlock on both wires.
- 3. Check voltage drop during the pulse.
- 4. Compare current with a good door.
- 5. Inspect hinge-area wiring.