When your BMW gets into an accident and airbags are deployed, there is another silent thing that happens - the vehicle cuts power either from the fuel pump or from the starter depending on the year and model of the car. So, you won't be able to start the vehicle even if the accident actually was minor.
There is a killer switch or the BST (battery safety terminal) in the positive terminal of the battery in your BMW and it cuts the power to prevent shorting and fire. You still can start your BMW when this happens but you will need to do a little magic with the safety terminal first.
Let's see how exactly you can start and why this happens in your BMW.
Why does the BMW cut power after accidents?
One of the reasons why there were so many fires after car accidents is that the electrical circuit may short. Once two cables or connections touch, they may cause shorting. They will heat up like crazy and may eventually cause fire.
In newer cars, manufacturers came up with a certain way to prevent these issues. While other companies may apply other killer switches, the BMW uses the BST or Battery Safety Terminal.
This is the simple thing that disconnects one of two cables attached to the positive terminal. Your car will still have the power to open the doors or windows or to switch on emergency lights. But it won't have any power on the starter motor or the fuel pump.
Now you know that the problem is in the battery compartment. So, let's see what exactly you can do to start your BMW.
Starting a BMW after an accident
If you press the start button or turn the key and get no engine cranking or the engine cranks but doesn't start, it means your BST is blown and you need to fix it. For this, follow these steps:
- Locate the battery which is, in most cases, placed in the trunk of your car, under the floor.
- Find the positive terminal and break into the plastic cover - you will need some pliers or other tools to do that.
- Find the disconnected cable - one of the cables will be disconnected from the terminal inside that red box.
- Push the cable back into its place and make sure it holds properly.
- Now start your vehicle and drive.
But before you can drive, you should make sure that it's absolutely safe. If your car is heavily damaged, there is no chance you can safely drive, so don't even touch that BST, in this case. Eventually, you may pay even more money for the repair if something shorts and gets fried.
Also, make sure that the deployed airbags don't disturb you from driving. You should cut them or at least fold them back into their places to make sure they won't limit your visibility or the ability to control your car.
Will this fix the problem forever?
Unfortunately, pushing the BST cable back into its place is only a temporary solution. Your safety system will require resetting and repair as well as several sensors that work as immobilizers, kill switches, and airbag control units. After the accidents, those need to be reprogrammed or replaced depending on the damage.
Also, you will constantly see the check engine light and newer vehicles will also show some warning messages on the dash. So, this method of pushing the cable back is a temporary solution that will allow you to drive to the dealership or repair shop.
If your car is under the warranty, I believe it's much safer to call BMW before you do anything with the battery terminal. They may pay for a tow truck, send a roadside assistance team to you, or tell you more about the warranty rules. If you just destroy the BST system, they may then refuse to pay for any repairs that could have been done under warranty.
How long can I drive like that?
This is a certain life hack that is not approved officially by BMW, so you will take some risks. I don't recommend driving your car a lot in this condition. You don't have a good deal of the safety systems working in your car. Also, you certainly have issues with the battery that can get disconnected again at any moment right when you are driving.
So, the best choice is to go to the dealership or to the repair shop with this problem. If you got into an accident and need to leave your car like this for some time, it's best to put it into your garage and not drive for some time till the insurance company or police do their job and let you repair it.
About the authors
The CarAraC research team is composed of seasoned auto mechanics and automotive industry professionals, including individuals with advanced degrees and certifications in their field. Our team members boast prestigious credentials, reflecting their extensive knowledge and skills. These qualifications include: IMI: Institute of the Motor Industry, ASE-Certified Master Automobile Technicians; Coventry University, Graduate of MA in Automotive Journalism; Politecnico di Torino, Italy, MS Automotive Engineering; Ss. Cyril and Methodius University in Skopje, Mechanical University in Skopje; TOC Automotive College; DHA Suffa University, Department of Mechanical Engineering
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