Case Studies

Reasons for Door Lock Actuator Failure in Your BMW

Reasons for Door Lock Failure in Your BMW
BMW is known for its luxury and performance. Car owners have fallen in love with the brand for its innovative technology. However, being one of the auto industry leaders doesn’t mean that there are no minor issues from time to time. Door lock failures can be a common problem BMW owners, and other car lines as well will face. To correct the problem, you need to know the reasons why these issues happen, and understanding some basics can help you guide your service professional when you report the symptoms. Here are some of the more common reasons why door locks fail, and what it occurs.

Blown Fuses
Blown fuses are a common occurrence in door lock systems. The good news is that fuses can be easily replaced and isn’t costly.
It’s a quick fix for many, but you still have to know why your fuse blew in the first place. If your BMW door locks are the only system affected, then the fuse is the culprit, but if there are other systems going haywire, you will need to identify the source of the problem. The more information you can supply, the more helpful it is to your service provider.

Important Tip – Fuses do not fail on their own, they do not “wear out”, and a blown fuse is a warning that something is a problem in the system. Never attempt to replace a blown fuse with a higher current rating, this can result in major electrical damage or even cause a fire.

Faulty Key FOB Or Remote
Key FOBs are one of the perks of advanced technology. You can unlock and lock your car, arm or disarm your car alarm, or even close and open the trunk remotely with just a push of a button. When key fobs malfunction, you will surely encounter door lock problems with your BMW.

It could be a dead battery or a glitch in your key fob programming. A simple battery replacement can sometimes solve the problem and is an excellent place to start when solving your door locking issues. We can also program and reset the FOB to the car’s computer, this is sometimes required with a dead battery or jump start when an electrical glitch occurs in the system.

Wiring Problems
BMWs are wired differently compared to other cars, and these complex systems may malfunction, particularly in the area of the door harness, which flexes each time the door is open or closed. This is often difficult to track down, and duplicate in the workshop, and is a frequent cause of fuses blowing intermittently. 

If the key fob and fuses are working, the next culprit is the wiring in your BMW’s electrical system. Wiring is not something that we often think of as wearing out, but through repeated use, it actually can burn out and become faulty. Often with wiring issues, you will notice fluctuations in power that will result in door locks working sometimes but not others, similar to low (but not quite dead) key fob batteries.

Replacing the wiring does not require taking apart your entire vehicle, as there are usually separate electrical systems for different parts of your car, but it will involve taking your door apart and getting to the battery. You will definitely need a professional BMW technician to take care of wiring issues in your vehicle.

Faulty Door Lock Actuators
A final common cause of door lock failure is when the door lock actuators malfunction. These actuators are the electronic mechanisms that physically engage the door locks when the lock button is pressed. These do not usually deteriorate quickly, but excessive use will wear them out over time, and the door locks are one of the most used functions of your BMW. How will you know if your door lock actuator is going bad?

Symptoms of lock actuator failure include weird noises coming from the door locks when operated or automatic locking and unlocking even when the buttons are not pressed. Likewise, intermittently blown fuses can signal an actuator motor that is drawing too much current and will eventually fail. Failure can be manageable at the onset, but you need to get them replaced if you don’t want to get locked out of your car.

Control Modules
A control module failure can cause issues with your locking system. Diagnosing the problem is not an easy task, but the failure of these modules is, fortunately, a rare event, usually caused by battery issues, jump-starting, or water intrusion. These units contain security coding and need to be diagnosed and programmed correctly by our BMW computer. You will need a professional BMW technician, equipped with the BMS ISTA computer, to program your system after service.

Have Questions?
For more information or questions on your BMW, please call one of our Service Advisors, they can offer valuable information on the proper service and repair for your car.

Our Goal For You and Your Car
Our goal is to save you money, not spend it. Which is why each and every car that we service gets a free Courtesy Maintenance Inspection during its first visit, and every subsequent visit.

Our goal is to let you know about the small problems, before they become big ones. Right now we have number of customer cars with well over 200,000 miles, and several approaching 300,000! And these cars are not just limping along – most look and drive pretty much the way they came out of the showroom. Proper maintenance is an investment in the life of your vehicle. Be sure it is properly performed, take it to Atlantic Motorcar…Extraordinary Service for Extraordinary Cars. (207) 882-9969

Questions, or if we can be of help in any way with service on your Audi, BMW, Mercedes, Mini Cooper or other European (and now Japanese) import, please contact us. Our team of Service Specialists is here to help, for even the newest autos! (207) 882-9969.

Knowing, not just “doing”, that’s the Atlantic Motorcar Center way.

The Atlantic Motorcar Center Service Team

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