4 SYMPTOMS OF A BAD BODY CONTROL MODULE (BCM)
PURPOSE
The purpose of the body control module is to control the electrical accessory system. Here is a list of items it controls:
Anti-theft
Instrument cluster
Windows
Locks
Climate control
Audio & navigation
Exterior & interior lighting
Mirrors
Alarm/immobilizer
Seating
Wipers
Windshield washer
Some blower motors
Horn
location
The location of the body control module varies between cars. It could be on the driver’s side to the left of the brake pedal, behind the dashboard, or under the center console.
When it comes to symptoms it really depends on how your BCM got affected. Maybe a specific circuit inside the BCM is corroded and only allows certain accessories to work, or maybe there was a complete failure resulting in no accessories working at all. Today, we will be discussing symptoms that could potentially happen with your car.
symptoms
engine light
The first symptom of a bad BCM is having a check engine light on. You could have multiple codes that have to do with the BCM and the circuits it controls. However, the most common code when the BCM goes bad is the U0140 code, which means there's no communication with the BCM. Make sure there are no torn wires or corroded connectors, as these can also cause this code to appear.
Ensure you can access your car's diagnostic codes by acquiring an OBD2 scanner here.
accessory failure
The second symptom is the accessories not working as they should. The non-working accessories can vary from car to car. Here are some examples that could happen. For instance, you turn on your high beam lights, and your windows roll down. Or you turn on your left turning signal and the car honks as well. Basically, since the BCM does not work properly, any electrical accessory in your vehicle can act strangely and dysfunctional.
only certain accessories working
The third symptom of a faulty BCM is only certain accessories working. Similarly to the previous symtpom this can vary from car to car. For example, your wipers, locks, and windows may not work, while all other accessories in your car can work just fine.
no crank no start
The fourth symptom of a bad BCM that can happen is a no crank no start. If the body control module is faulty, it can lose communication with the ECM, and as a result, it will prevent your car from starting.
Before assuming that you have a bad body control module, make sure to check for blown fuses, torn wires (that connect to the BCM), and corrosion (at the pins of the BCM & at the wiring harness connector). Sometimes water can get in between the connectors and the pins, which will cause corrosion. If you’re lucky, you can get your BCM working again, by cleaning it with this cleaning spray.
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