Your bmw battery replacement has a 2-year-old. Your car died one morning when everything seemed fine. Your beloved BMW’s battery is dead—no lights, iDrive, or starter. You used a touchless car wash with undercarriage spray the night before. You wonder if water got in. You’re looking for answers. bmw battery replacement troubleshooting instructions.
Buy a battery afterwards. Do not rush to the dealer if you have aftermarket equipment like a DVD player, since they will likely blame the dead battery on those and insist you remove them before rechecking.
Most BMW owners on forums say that if your car isn’t under warranty, the dealer will sell you a new battery. If it fails, they may sell you an alternator and other electronic modules.
Conclusion: troubleshooting the dead battery yourself may be faster and cheaper. Try these simple steps before buying pricey replacements.
Car battery charging
The battery must be recharged before testing.
BMW battery charging—how?
BMW suggests charging the battery using the underhood jump start connectors. Slowly charge your battery by connecting the red clamp first. Charge a dead battery for 24 hours. Keep the key out when charging.
Another option is to unplug the battery from the car, move it to a charging station in your garage or residence, and let it fully charge. Battery chargers usually indicate full charge.
BMW battery draining?
BMW excessive battery drain causes and tests:
Plugged-in external devices
Plugged-in OBD-II scanner
BMW Intelligent Battery Sensor
The infamous “hedgehog” (climate control panel)
One of your car’s electronics drains too much power or doesn’t go into sleep mode
The car engine powers an alternator, which recharges the battery while the car is moving. The automobile recharges itself.
This only works with the engine running. The car uses a limited battery when parked. The battery is only being drained by the plugged-in device. This is why forgetting your headlights caused the dead car surprise when you returned.
If you recharged a dead battery, unplug any external power consumers. Cigarette outlet chargers or adapters?
Connected OBD-II scanner
Depending on your OBD-II scanner, keeping it plugged in may not be a smart idea. Some OBD-II scanners use greater electricity. When idle, this can drain the battery. Leaving an OBD-II scanner plugged in overnight is unlikely. BMW Intelligent Battery Sensor (IBS).
The 5 Series BMW (E60, E61) and 3 Series (E90/E91/E92/E93) contain an Intelligent Battery Sensor (IBS) on the battery negative terminal (the “-” or “black” terminal).
Battery sensor function?
The IBS microprocessor monitors voltage, current, temperature, starting current, and closed-circuit current. The IBS constantly monitors the car. To conserve battery power, the IBS wakes up every few seconds, tests, then goes back to sleep when the car is parked, bmw battery replacement.
Early E60 and E61 versions had IBSs that leaked moisture and corroded. The masses had IBS. Later 5 Series and 3 Series have IBS issues. A defective IBS prevents your car from switching into sleep mode and drains the battery.
Testing IBS for defects
Disconnecting it from the battery’s negative terminal tests the flawed IBS hypothesis. Remove this little module’s red wire to disconnect the IBS. BMW battery IBS removal videos exist online services.
Disconnecting the IBS stops battery draining. Buy a new IBS online
BMW E39, E46, and E53 Final Stage Resistor (FSR), known as the “Hedgehog,” drains batteries in large quantities. The FSR is spikey like an enraged hedgehog, hence its name. It’s called blower motor resistor or heater fan resistor.
FSR is linked to your car’s HVAC system (Heating, ventilation, and air conditioning). However, aircon, ventilation, and other concerns are not expected. Some say the car fan stays on after shutting down.
No hedgehog is needed to test your FSR. Remove this component’s fuse. Check your BMW user handbook to find the FSR fuse. Search online for your e39’s user manual since you probably don’t have one. Or watch an FSR replacement video online.
Module doesn’t sleep or drains power.
Telematics controller (TCU)
See if your automobile has a TCU. Faulty batteries drain from this. View the BMW TCU. TCUs are behind the trunk trim. Find the TCU with online videos.
Replace the unit’s fibre optics connector with a MOST loop female bypass connector to test the defective TCU theory. If you don’t have a MOST bypass connector, keep it unconnected. This may also disconnect your sound amplifier. It’s harmless, but you won’t hear music until you reattach the TCU or instal a MOST loop connector. It will easily and cheaply test if your TCU is causing the dead battery.
BMW TCU repair can fix a dead battery caused by the TCU.
iDrive main computer (navigation)
CCC and M-ASK iDrive navigation modules frequently drain batteries overnight. Either:
Find and disconnect units. Pull the rear-panel connectors to detach the M-ASK or CCC iDrive. Remove the modules from the dashboard to access the rear panel (there are plenty of video guide on YouTube)
Look up your car’s fuse diagram, find the CCC or M-ASK fuse, and temporarily remove it.
CCC repair services are available if CCC failure is confirmed. For MASK iDrives, we offer M-ASK repair. Although both are repairable, the dealer won’t fix them. Replacement units cost much more than 1-year warranty repairs from the dealer.
Whether your automobile does not contain the above three electronic modules, you can still check to determine if one is draining your battery. This automobile short-finding video is instructive, simple, and fun.
Bad alternators don’t charge batteries. Some vehicle shops offer complimentary charging system tests. If you can’t find one, pay for a test before buying a new OEM battery.
Replacing your car battery is your final choice, hoping it was too old and weak. BMW OEM batteries are costly. OEM batteries aren’t necessary. ACDelco or DieHard batteries work fine. Choose a new battery that matches your OEM battery as closely as feasible.
You can change your BMW battery yourself, at the dealer (if you buy the OEM costly battery), or at an independent repair shop, not necessarily BMW-endorsed.
Reprogramming BMW batteries?
Many online resources and the dealer recommend registering and coding your new battery following installation. If you replace your service b mercedes at an independent store, inquire about this option or do a more in-depth online search for your car model. Some DIY enthusiasts report no problems from using a new BMW battery without coding. Read more