Why Control Modules Fail: BCM, Airbag, ECU, and PDC Explained

Modern vehicles rely on control modules — small but powerful computers that manage nearly every system in your car. From safety features to engine performance and parking sensors, these modules communicate through a complex network to keep everything running smoothly.

At Andre Parts we provide tested used control modules — including Body Control Modules (BCM), Airbag Control Units (ACU), Engine Control Units (ECU), and PDC Modules — all at a fraction of OEM dealer prices.


🧠 What Do These Modules Do?

1. Body Control Module (BCM)

The BCM is the central brain for your car’s electrical systems. It manages:

  • Power windows and locks

  • Interior and exterior lighting

  • Wipers, mirrors, and alarm systems

When a BCM fails, you might notice random electrical glitches — lights flickering, doors not locking, or the car refusing to start.

🔗 Browse tested replacements in our Body Control Module collection 


2. Airbag Control Unit (ACU)

The ACU monitors crash sensors and triggers airbag deployment when needed. It’s a critical safety component.
Failures usually happen after an accident, water damage, or electrical short — leading to an airbag light that won’t turn off.

🔗 Find quality Airbag Control Units for most makes and models.


3. Engine Control Unit (ECU)

The ECU controls your car’s engine performance, fuel injection, and emissions. When it fails, you might experience:

  • Check Engine Light

  • Rough idling or misfires

  • Loss of power or poor fuel economy

Instead of paying dealership prices, explore our Engine Control Unit selection — all tested and ready to install.


4. Park Distance Control (PDC) Module

The PDC module powers your parking sensors, helping you avoid obstacles while reversing.
When it fails, your sensors might beep continuously or stop working altogether.

🔗 See our PDC Modules for affordable replacements.


⚡ Why Control Modules Fail

Even though these modules are engineered for long life, they’re still vulnerable to:

  1. Water and Moisture Damage
    Modules near the floor or under seats (especially BCM and ACU) are prone to corrosion.

  2. Voltage Spikes
    Jump-starts, dead batteries, or alternator issues can damage sensitive circuits.

  3. Heat and Vibration
    Over time, solder joints crack, especially in ECUs mounted near the engine.

  4. Software Corruption
    A bad reprogramming attempt or low battery can corrupt firmware and cause errors.


🔍 How to Spot a Bad Module

Symptom Likely Cause
Warning lights (Airbag, Check Engine, ABS) ECU or ACU fault
Electrical issues (lights, locks, wipers) BCM fault
Parking sensors not working PDC module issue
Car won’t start or random electrical failure BCM or ECU malfunction

If you’re unsure, contact Andre Parts — our experts can help you identify the right replacement for your vehicle.


🔧 Why Choose Used OEM Modules

Genuine OEM parts – perfect fit and performance
Fully tested before sale
Cost savings up to 70% vs new
Eco-friendly – reusing parts reduces waste

At Andre Parts  each control module is inspected, tested, and guaranteed to work before shipping.


🧰 How to Replace a Module Safely

  1. Disconnect the vehicle’s battery.

  2. Locate the module (under dash, behind glovebox, or near fuse box).

  3. Remove connectors carefully.

  4. Install the replacement securely.

  5. Some modules (like ECUs or BCUs) may require programming — check compatibility with your VIN.

💡 Need assistance? Reach out via our Contact Page — we’ll guide you through it.