It is a truth universally acknowledged that modern BMWs have electrical systems controlling more processes in them than ever before. These systems keep us safer, like lane assist and automatic braking, make our drives more enjoyable, like heated seats and climate control, and allow you to customize your driving experience in ways the BMW founders never would have dreamed of 100+ years ago. The only problem with more electrical systems in your car is that there are more BMW electrical things that can go wrong.
Luckily for you, we’ve quizzed our BMW mechanics and they’ve given us a few things to look out for if you are having BMW electrical issues.
Always Check The Battery: A Weak One Causes Problems
You really can’t underestimate the importance of a strong battery in any car, whether it is a fully electric model or if it is connected to a traditional internal combustion engine. The battery is what gives your car that spark of power to get it started when you turn it on. Though the battery is automatically charged by your alternator when your car is running, your car’s battery won’t hold a charge forever, just like the AA batteries in the back of your TV remote.
If some of the electronic devices in your car are not working correctly, or strange error messages are showing up, checking the battery’s power is a good place to start. When it comes to BMWs, there is a device called the body control module that is in charge of the car’s CAN bus electrical system—which tells the car’s computer what to do when you hit a button. If there isn’t enough power to the body control module, you can sometimes get all kinds of errors about things like faulty sensors or other electronic devices. Though something may be wrong with the sensors unrelated to the battery power, if the battery is low on power, the module may not have enough power to communicate with all of the sensors, so it thinks there is something wrong with them.
Pay Attention to Things That Drain The Battery Fast
When you’ve had a battery for a while will eventually need to be replaced. The general rule of thumb is to expect 3-5 years for a battery in a car with an internal combustion engine. One thing that may contribute to a bad battery earlier than you would expect is if you have your car’s start-stop feature turned on regularly. This function turns the car off when idling and then back on when it is time to go, and puts extra strain on the battery, as the car is using an extra spark of electricity from the battery to start the engine each time. These stop-start systems are designed to monitor the battery’s charge to prevent you from being stranded in a traffic jam, but you may have to replace the battery more often if you keep this gas saving function turned on.
It’s also important to note that in some of the bigger BMWs have two batteries. So if you’ve checked one and the charge looks fine, make sure there isn’t a second battery that might be dead. If one is dead, it will cause BMW electrical issues and error messages.
Is Your Battery Even Connected? Check the Terminals
It may seem like a strange question to ask whether or not the battery is connected. Unless someone has been messing around under the hood, you would think that the battery would remain connected, but this isn’t always the case. BMWs have an important safety feature built into the battery connection called the battery safety terminal (BST). In the event of an accident, this device automatically disconnects power from the battery to the engine to make sure that there isn’t a catastrophic fire. The BST device is designed to explosively disconnect power from the battery when airbags have been deployed.
From time to time, however, especially on older models, one of these BST devices may detonate after something like hitting a particularly big pothole or after being next to a faulty battery that is off-gassing. If you hear a loud pop from under the hood, after which the airbag light comes on, and the car won’t restart, but the lights still work, you may have a blown BST device on your hands.
A BMW Electrical Question: Is Your Alternator Holding Up?
If you replaced the battery recently and it doesn’t seem like it is holding a charge, it may be the time to take a closer look at your alternator. In addition to charging the battery, the alternator works together with the battery to power all of the other electric parts of your car. This includes things like the lights, heater, infotainment screen and more. If you press a button on your dash and something happens, the alternator is involved.
If you notice things like dimming lights when you hit the gas, you should have a BMW electrical specialist run a test on your alternator.
Don’t Make The BMW Steering Wheel Angry: The ELV Fault
Another interesting BLW electrical problem is an ELV fault. If the ELV (electric steering lock) doesn’t like how you are yanking on the wheel when parking, or leave the wheels at a hard angle when you’ve turned off the car, your BMW may lock your steering wheel in place to prevent further manhandling. This lock shows up on your dash as either a yellow or red steering wheel with a little padlock in the corner.
Though this lock will usually go away once you’ve started the car and finessed the wheel, the fault may cause the lock to get stuck on (another potential symptom of a weak battery) and remain on even when the battery is replaced. If you can’t get your ELV fault to go away on your own, a BMW electrical specialist may be the answer to your problems.
Sometimes A BMW Electrical Specialist is All You Need
The fact of the matter is that no matter how many tutorials and suggestions you read online on how to fix a BMW electrical problem, sometimes you just need an expert. Sure the auto repair shop will cost more than a DIY fix, but the amount of time you spend tinkering could be spent on other, more enjoyable pursuits. And when you take your car to a BMW mechanic and say, “fix my BMW,” you will know that your BMW electrical repair is done right.
