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Learn how to go about diagnosing a fault in a car door that won't open, using a Snap-on diagnostic platform and lab scope to help you to the answer.

A driver brought his vehicle – a 2008 Volkswagen Golf 1.9L – to be checked out as the front driver’s side door would not open.

After initially testing and verifying the complaint, a Snap-on VERUS Edge scan tool was connected to the vehicle and the following fault codes were located:

  • 00097 - Front Passenger's Central (Safe) Motor (V162) Electrical Fault In Circuit
  • 00929 - Locking Module For Central Locking: Front Passenger Side (F221) Implausible Signal

The VERUS Edge was used to monitor the status of each of the vehicle’s door locks during further testing, which involved pressing the locking buttons and examining the results on the scan tool.

All of the doors were operating correctly apart from the front driver’s side as the parameter remained in “Safe” mode while the others changed in accordance with the buttons being pressed.

The door panel was removed in order for a visual inspection of the door lock, which found no clear problems, so a Snap-on lab scope was used to monitor the voltage at the door lock switch.

This found that voltage and the control signal were both present, indicating that the door lock itself was faulty.

After the door lock was replaced, the VERUS Edge was reconnected to the vehicle to clear the fault codes and then a manual test confirmed that the door was now able to be opened, closed and locked correctly.