Programmed 2009 XLR Engine Module 12636659 | ECM ECU Computer

Restore Peak Performance and Reliability to Your GM Vehicle

Is your Cadillac, Corvette, or Hummer suffering from frustrating issues like a persistent check engine light, erratic idling, stalling, or poor fuel economy? These are classic signs that the vehicle’s brain—the Engine Control Module (ECM)—is failing. As a technician with over two decades of experience, I’ve seen firsthand how a faulty ECM can cause a cascade of problems that are often misdiagnosed. This isn’t just a part; it’s the central command center for your engine’s performance, and when it falters, your vehicle’s reliability is compromised.

This Engine Control Module, part number 12636659, is the definitive solution. We take the guesswork and hassle out of the repair by pre-programming the module specifically for your vehicle using your VIN. This means it arrives at your door with the latest GM factory software updates already installed, making it a true plug-and-play replacement. You get a reliable fix that restores factory performance without the exorbitant costs and scheduling headaches of a dealership visit. This is the same high-quality component I would confidently install in a customer’s car in my own shop.

Is Your Vehicle Showing These Symptoms?

• ✔ Check Engine Light is on with codes like P0601, P0606, or U-series communication codes.
• ✔ Engine cranks but refuses to start.
• ✔ Noticeable decrease in fuel efficiency.
• ✔ Rough or unpredictable engine idling.
• ✔ Vehicle stalls unexpectedly while driving or at a stop.
• ✔ Hesitation or stumbling during acceleration.
• ✔ Automatic transmission shifts harshly or at the wrong times.

A Straightforward Guide to Installation

Replacing your 2009 XLR Engine Module is a manageable job for a confident DIYer. Just follow these steps carefully.

1. Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
2. Locate the ECM: On most of these vehicles, the ECM is located in the engine bay, often on the firewall, inner fender, or near the air cleaner box. Check your specific model’s service manual for the exact position.
3. Disconnect Connectors: Carefully unlatch and remove the wiring harness connectors from the old module. Inspect them for any corrosion or damage.
4. Remove the Old Module: Unbolt the mounting hardware holding the old ECM in place and remove it from the vehicle.
5. Install the New Module: Mount your new, pre-programmed ECM in the same location and secure it with the original hardware.
6. Reconnect Everything: Firmly plug the wiring harness connectors into the new module until they click into place. Reconnect the negative battery terminal.
7. Final Check: Turn the key to the ‘ON’ position (without starting) for 10-15 seconds to allow the system to initialize. Then, start the vehicle. The check engine light should be off, and the engine should run smoothly. Note: Some vehicles may require a security or crankshaft position sensor relearn procedure, which can be done with many mid-range scan tools.

Verified Vehicle Compatibility

This module is a direct replacement for a wide range of GM vehicles. Please confirm your model and engine below. It is interchangeable with service numbers: 12639300, 1263605, 12628993, 12628911, 12625453, 12622175, 12630464, and 12678512.