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Usual Symptoms of Failing Body Control Module (BCM) That You Want to Know

Usual Symptoms of Failing Body Control Module

Usual Symptoms of Failing Body Control Module

The Body Control Module (BCM) is the central organizational element of your car that controls other security systems of the vehicle. The BCM contains information which lets you know directly concerning a system that is malfunctioning and out of control. This system gives you efficient troubleshooting features and manufacturing details by enclosing it to one component or central unit and not the conventional single function with its own device.

This article will let you figure out what’s happening to your BCM the moment it malfunctions. Problems on this system will trigger series of events that can give rise to extensive damage to your car. This write-up will also give you hints on the various Body Control Module’s symptoms of failure when this control unit is trying to say something about your car.

Body Control Module (BCM)

Why does a BCM fail?

These various reasons may trigger a failure on the part of the Body Control Module. You should be aware of these events so you would know what are their effects on your car’s BCM.


Water contamination

This system is typically waterproof, but there could be ways one or the other that water may seep through the system. When this happens, sensors might suffer short circuit which will leave them unable to read the correct data.


Extreme heat

When the BCM is exposed to extreme heat, especially during summertime, the function of this system might be undermined and may not give you accurate results. Excessive heat may come from the car’s engine or the surroundings.


Extensive shock

The BCM could be in danger of failure when your car suffers shock from a collision and other similar accidents. The most important thing to do is to drive carefully and safely.


Tear and wear

The longer amount of time of service may render your BCM to suffer the usual wear and tear that normally happens to all parts of your car. This system is not immune to this phenomena.


Extensive shaking or vibration

The abnormal vibration that happens frequently will also lead to your BCM to malfunction. Rough roads and other similar terrains where you drive every day may cause the system’s failure.

What are the symptoms of a malfunctioning BCM?

Here are some of the symptoms that you may notice on your car when your BCM is malfunctioning.

1. Flashing or lighting of “Check Engine Light” and other warning lights

As the BCM is communicating with other control elements of your car, its accomplishments of various functions may be hindered. For example, a defective BCM may trigger dashboard instrumentation cluster error and the car’s warning lights may flash on and off (such as the “check engine light”). But the BCM may not be able to interpret its meaning as it will not read the sensors accurately.

Related post: ​What Do “Engine Reduced Power” and “Check Engine” Lights Mean

2. Engine may not start

A “no crank” or no start status on the engine may be observed when the BCM malfunctions. This is primarily because of the BCM’s miscommunication with other control systems of the vehicle. When this warning sign is detected, better to consult your expert mechanic.

3. Draining of battery

Also called as “parasitic drain”, this condition is somewhat normal in your car. When you are on parking, the battery is strong enough to supply your other car components with energy to run them, such as the radio presets, security alarm, and other elements. But a malfunctioning BCM may not detect other parasitic drains that will leave you with a drained battery.

4. Errors in key operations

When you have a failing BCM, these security features’ operations might be in jeopardy:

  • Vehicle Anti-Theft Security System (VATSS)
  • Passive Ant-Theft System (PATS)
  • Remote Keyless Entry (RKE)


As much as you want to know more about the Body Control Module (BCM) of your car, when it fails and replacement is sure to happen, it is better that your most trusted mechanic or technician do the job. As we have taught you the reasons and symptoms of a malfunctioning BCM, fixing this unit requires fixing the hardware while its software might need reformatting using special tools.

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