Service function guideCentral Locking Diagnosis

This central locking diagnosis guide gives working mechanics and experienced DIY owners a structured, door-by-door method for tracing faults in remote, keyless and manual locking systems. It explains how the system's inputs, control module and actuators interact, then walks through preparation, isolation, measurement and confirmation so you can pinpoint a failed component instead of replacing parts by guesswork. You will be able to read a wiring diagram, test a door latch actuator and interpret voltage, resistance and scan-tool data with confidence. The guide also covers variations between vehicle types, common diagnostic mistakes, failure recovery and the aftercare that prevents repeat comebacks.