Have you ever been in a situation where you are outside your Mercedes, with keys in hand, but the doors will not open? If so, then it could be a vacuum door lock failure that you are experiencing. Most modern Mercedes-Benz vehicles use a vacuum system for locking and unlocking their doors. This system usually relies on things like actuators and vacuum lines.
When you press the door lock or unlock button, the vacuum pump is activated and it creates the pressure needed to move the door locks. A door lock issue is a very common problem so there’s no need to panic. Below is a brief guide that you can use to diagnose and repair the vacuum door lock failures in your Mercedes.
Diagnosing Vacuum Door Lock Problem
- Check Vacuum Pump: This component is usually housed in the trunk of the car. To know its condition, pay attention to the sound of the pump when you touch the lock or unlock button. If you do not hear anything, there is a possibility that the pump is out of order.
- Inspect Vacuum Lines: Check the vacuum line for any signs of damage, or cracks or if it has been disconnected in any way. The vacuum line has areas where the lines are bent or are passing through a tight space; these points should be given more attention since they are most prone to breakage.
- Test Actuators: Every door is equipped with a vacuum actuator that controls the lock. Check each of the actuators using a hand-held vacuum pump by applying vacuum pressure on them. If an actuator cannot maintain pressure, it might be time for a replacement.
- Check the Vacuum Reservoir: The vacuum reservoir on the other hand stores vacuum pressure. Check that it is not broken or chipped as this can cause the loss of pressure in the system.
Repairing the Vacuum Door Lock System
- Replace Vacuum Pump: If this component is not functioning, then you will have to change it. Before starting the replacement, remove the battery connection from the vehicle. Take out the old pump and disconnect all electrical as well as vacuum connections from it. Replace the pump with the new one, reconnect all the connections, and then run the system.
- Repairing Vacuum Lines: If you find out that any of the lines have been damaged or cracked, then you will need to repair or replace them with a new one. For small cracks, a repair tape can be used. It is necessary to replace the entire line with a new one if you see major cracks. Make sure the new lines are properly connected and there is no leak.
- Replace Actuators: If one or more of the actuators are bad, replace them with fresh ones. Take off the door panel to get to the actuator. Remove the old actuator and replace it with the new one and make sure it is fixed correctly to the vacuum system.
- Fix Vacuum Reservoir: If for some reason the vacuum reservoir is damaged, then it will have to be replaced. Remove the old reservoir and then fit the new one. Check that all vacuum lines are properly connected to the new reservoir.
When to Go for Professional Assistance
Even though some door lock problems can be solved through minor DIY fixes and modifications, other problems may need the services of a professional. If you do not feel confident in diagnosing or fixing the system yourself or if the problem remains after trying simple tricks, it is advisable to consult a mechanic. A competent technician can identify the issue and fix it to ensure that your Mercedes door locks are working as they should.
Los Angeles Drivers Trust Carotech Automotive With Their Mercedes
At Carotech Automotive, we are your 
local experts in the maintenance and repair of luxury European automobiles such as Mercedes-Benz. If you are having problems with vacuum door lock failure in your Mercedes, our professional mechanics will be happy to help you identify the problem and repair it as soon as possible.
Being a company that focuses on quality services and customer satisfaction, we guarantee that every repair is done to the best standards to have your car’s performance and comfort back on track. Our garage is based in Los Angeles, CA and we are always willing to help clients within the neighboring regions. Do not let door lock problems get in the way of enjoying your car – schedule your next Mercedes service now!
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