A scan tool can show that a movement was requested without proving that the mechanism reached its target. Command, electrical drive and feedback are separate pieces of evidence.
How to narrow it down
Record each available stage during the fault and identify where the expected response stops. If the command never arrives, investigate the conditions that permit it. If drive is present but movement or feedback is wrong, assess the relevant electrical and mechanical paths.
What to include with the fault report
Include the requested state, actual position and any current or voltage measurements.
Avoid describing an actuator as tested solely because the command button was pressed. The observed result and test limits should be recorded.
Speak to AXION
For complex vehicle-electronics diagnostics, send your vehicle details and fault report. Workshop assessment is in Didcot, Oxfordshire. Suitable postal or remote work is confirmed before booking.
Technical background from Texas Instruments. The referenced design explains the principle; the vehicle-specific procedure determines the repair.
Related reading — H-bridge motor voltage should be interpreted across the motor. Browse all vehicle-electronics diagnostic notes or return to the repair library.