Restore Your Vehicle’s Core Performance
When the Engine Control Module (ECM)—the central computer of your vehicle—starts to fail, it can cause a cascade of frustrating and unpredictable problems. From a car that won’t start to poor fuel mileage and a persistent Check Engine Light, a faulty ECM can make your vehicle unreliable. This isn’t just a part; it’s the brain behind your engine’s performance, managing everything from fuel injection to ignition timing. This replacement ECM, part number 12678512, is the definitive solution to restore your vehicle’s factory operation and your peace of mind.
As a technician with over two decades of experience under the hood, I’ve seen firsthand how a failing computer can mimic a dozen other problems. You can waste hundreds of dollars chasing ghosts in the system. Our process eliminates the guesswork. We take your vehicle’s VIN and flash this module with the latest, most stable software directly from GM. This means you receive a part that is 100% ready for installation, with no need for expensive dealership programming. It’s a direct-fit, plug-and-play solution designed to get you back on the road quickly and affordably. By ordering this 2009 XLR Engine Module, you’re not just buying a part; you’re buying a pre-configured, reliable fix.
Common Signs of a Failing Engine Computer
- ✔ The Check Engine Light is on, often with communication or internal processor fault codes (e.g., P0601, P0606, U0100).
- ✔ Your vehicle experiences intermittent or complete no-start conditions.
- ✔ Noticeable decrease in fuel economy and engine performance.
- ✔ Unexplained engine stalling, stuttering, or hesitation during acceleration.
- ✔ Automatic transmission shifting becomes harsh or erratic.
- ✔ Other warning lights on the dashboard may illuminate without a clear cause.
Case Study: The Ghost in the Corvette
A few years back, a 2009 Corvette ZR1 came into my bay with a truly baffling issue. The owner complained of random power loss and stalling, but it would never act up for me. We checked fuel pressure, sensors, and wiring harnesses—everything seemed perfect. The only clue was an intermittent U0100 ‘Lost Communication with ECM’ code that would pop up and disappear. After exhausting all other possibilities, we suspected the ECM itself had an internal fault that was only triggered by a specific combination of heat and vibration. We installed a VIN-programmed ECM, and the problem vanished instantly. It was a powerful reminder that sometimes the most complex issues have a straightforward solution if you replace the core component. That’s the certainty this module provides.
A Straightforward Guide to Installation
- ✔ Safety First: Always disconnect the negative terminal from your vehicle’s battery before beginning any electronic component replacement.
- ✔ Locate the Module: On the 2009 Cadillac XLR, the ECM is found in the right-hand front engine compartment. Its location varies on other compatible models (see fitment list).
- ✔ Disconnect Connectors: Carefully release the locking tabs on the wiring harness connectors and pull them straight out from the module. Do not force them.
- ✔ Remove the Old Module: Unbolt the mounting hardware holding the old ECM in place and remove it from the vehicle.
- ✔ Install the New Module: Mount your new 2009 XLR Engine Module securely in place. Reconnect the wiring harnesses, ensuring they click and lock firmly.
- ✔ Final Steps: Reconnect the negative battery terminal. The vehicle may require a security relearn procedure, which typically involves turning the key to the ‘ON’ position for 10-15 minutes. This allows the other modules to recognize the new ECM. Start the engine and confirm the Check Engine Light is off.
Verified Vehicle Compatibility
This ECM is a direct replacement for a wide range of GM vehicles and is interchangeable with service numbers 12636659, 12639300, 1263605, 12628993, 12628911, 12625453, 12622175, 12630464, and 12678512. Please confirm your vehicle is on this list:
CADILLAC DTS (2009-2011)
CADILLAC SRX (2009) 4.6L
CADILLAC STS (2009) 4.4L, 4.6L
CADILLAC STS (2010) 4.6L
CADILLAC XLR (2009) – Fits IDs 12636659, 12625453
CHEVROLET COLORADO (2009)
CHEVROLET COLORADO (2010-2012) 2.9L, 3.7L
CHEVROLET CORVETTE (2009) ZR1
CHEVROLET TRAILBLAZER (2009) 6.0L
GMC CANYON (2009)
GMC CANYON (2010-2012) 2.9L, 3.7L
GMC ENVOY (2009) 5.3L
HUMMER H3 (2009-2010)
BUICK LUCERNE (2009-2011) 4.6L
SAAB 9-7X (2009)
Frequently Asked Questions
Frequently Asked Questions
Do I need to do any programming myself?
No. We handle all the programming before shipment. Simply provide your vehicle’s 17-digit VIN during checkout, and we will flash the module with the latest GM software specific to your car. It arrives ready to install.
Is this a guaranteed fix for my vehicle’s problems?
This module will correct issues directly caused by a failing ECM, such as internal processor faults (P0601) or communication errors. While it solves many common problems, we always recommend a proper diagnosis to confirm the ECM is the root cause before ordering.
Will this work for other part numbers?
Yes, this part is a direct replacement for several service numbers, including 12636659, 12628993, 12625453, and others listed in the description. It is a fully compatible, updated component.
What is a security relearn procedure?
This is a simple process that allows your vehicle’s anti-theft system to sync with the new ECM. For most GM vehicles, it just involves leaving the key in the ‘ON’ position for 10-15 minutes before starting the engine for the first time after installation.
How do I provide my VIN?
You can enter your VIN in the notes section during the checkout process or send it to us in a message after placing your order. We cannot ship your part until we receive the VIN for programming.