How to Replace a Bad Car Door Lock Actuator
How to Replace a Bad Car Door Lock Actuator

How to Replace a Bad Car Door Lock Actuator

The central lock is a device that allows you to close and open all the doors of your car automatically and simultaneously. This solution is convenient and functional, as well as quite reliable. However, after a long-term operation, as a result of using cheap parts, or in case of failure, the car door lock actuator can often break completely or work incorrectly (for example, one door can stop working).

In any case, if the central lock does not open one door or does not work effectively, you need to solve this problem, and to avoid such issues, you must find out and eliminate damage to the central locking drive. This article will address these points, highlighting potential reasons for car lock failure and how to repair it yourself.

Man hand opening car

When Do You Repair or Replace Your Door Lock Actuator?

So, how do you know that your door lock actuator needs to be changed?

Bad Door Lock Actuator Symptoms

Car owners may encounter a scenario where the central lock is triggered, but the functions have been broken. The doors may not close/open, the lock may not work on all doors, the doors may open and close at random, and so on. At first, the problem may only occur sporadically, but it will progress and worsen over time. The complete breakdown of the element means that the locks on the door will not open or close. To prevent this, you need to take quick measures on time.

However, first, you need to make sure every door can be opened and closed manually. That is how you understand your door lock actuator is bad, and the problem with isn’t associated with a different element in the door.

Car mechanic trying to fix door lock actuator

Door Lock Actuator Motor Replacement and Repair

Normally, replacing a door lock actuator will cost you less money than repairing it. Not sure how to fix a door lock actuator on your own? Firstly, let’s start with the possible malfunctioning reasons.

If an actuator on one or more of your car doors does not work, it could mean the following:

  • there may be an open or poor contact in the supply circuit, which goes from the actuator switch on the driver's door to the power relay (directly or through the board) to the problem drive.
  • the relay is defective, or the control board is out of order; the wires are broken or there is no contact at the motor terminals or actuator solenoids.
  • gears of the actuator motor or other mechanical parts are worn out, or the motor winding/coil on the solenoid has burned out.
  • Often, the central locking chains of a car are damaged in the corrugation passing between the door and the car body.

Car door lock actuator repair

The steps you need to follow once you have determined the automatic locking system isn’t working are as follows:

  1. The first step is equipment diagnostics. Note that the lock should work regardless of whether the door lock actuator motor is working or not, and whether the key is inserted in the ignition switch or not. Make sure the on-board network of the car machine works normally, the battery works, and is charged and is properly connected to the battery terminal.
  1. Check the voltage in the broken drive. Normally, the voltage should occur in one wire and only at the time of activating the closing function. If you activate the opening, the voltage moves to another wire. The condition of the wires should be evaluated: creases or insulation damage are not permitted.
  1. After analyzing the data obtained, you may need to check the connection of the actuator or circuit coming from it. Then, after checking the area in front of the relay, the wiring, the contacts of the control board, the board itself, the relay, the wiring for the relay, etc.
  1. From this examination, if you have identified the problem area, you can now repair it. Each element of the central locking drive requires checking, with particular attention to be paid to the most loaded areas that can be damaged mechanically (corrugations, insulation of wires, gears, hoses, pushers, etc.). If you cannot identify any issues, then you should check the contacts and terminals. Moisture and oxidation can often also cause the signal and voltage to disappear.

Mechanic installing car central door lock motor

How to Repair or Replace Door Lock Actuator

If the door lock on your car does not react to pressing a button on the key control, then the lock drive has probably worn out. Fixing it will take time, and the complexity of the work depends on the specific car model.

Generally, the procedure starts as follows:

  • Disconnect the battery from the on-board network.
  • Remove the inner door panel.

While disconnecting the battery is not a problem, working on the external and internal door panels can be challenging. Its fastening may consist of visible and hidden screws; on some models, the lock drive is built directly into the door latch. You can also face the need to dismantle the door glass.

The drive consists of two or three parts connected by plastic latches. We recommend taking a picture of each stage of disassembly so that you can assemble it back correctly.

After disassembly, check engine operation. For this, just connect it to a standard 9-volt battery. A malfunction of the switch is easy to determine - in this case, it has a dark terminal. Use sandpaper to clean the terminals. Once you’ve done that, the electric motor can be assembled and tested. If it still does not work, then it’s all about winding and it will be easier and cheaper to replace the motor with a new one.


If a car door lock does not work, there can be many reasons for it. However, it becomes clear that knowledge of the general device and electric central lock operation principles allow you to quickly find the problem. This insight will allow for accurate diagnosis and high-quality elimination of potential malfunctions.

If you need to repair or replace your car door lock actuator, our consultants will help you choose the right actuator model or actuator parts suitable for your car. Don’t wait until your broken lock becomes a nuisance or a danger: contact us now for a consultation.

Anna Sapiga

AZ Engineer

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