Restore Peak Performance to Your GM Vehicle
Is your truck or SUV suffering from frustrating, hard-to-diagnose issues? A faulty Engine Control Module (ECM) is often the hidden culprit behind problems like a persistent check engine light, poor fuel economy, stalling, or even a no-start condition. As the ‘brain’ of your vehicle’s engine, the ECM controls everything from fuel mixture and ignition timing to transmission shifting. When it fails, it can cause a cascade of problems that can be costly and difficult to pinpoint. This replacement Engine Control Module is the reliable, straightforward solution to get your vehicle running properly again.
This isn’t just a part in a box. We take the guesswork and extra expense out of the repair by pre-programming this module specifically for your vehicle using your VIN. This means it arrives at your door with the latest GM software updates already installed, ready for a simple, direct installation. You get to skip the expensive trip to the dealership for programming, saving you significant time and money. This is the most efficient way to fix your 2009 Envoy Engine Module and restore its factory performance and reliability.
Case Study: A Tricky Diagnosis
I remember a 2009 Trailblazer 6.0L that came into my shop with a maddeningly intermittent no-start condition, but only when hot. The owner had already replaced the fuel pump and crank sensor with no luck. After connecting my scan tool, I noticed that when the engine was hot and wouldn’t start, I’d lose all communication with the ECM—a classic sign. We let it cool down, and it fired right up. The original ECM, located right on the hot engine block, was failing from years of heat cycles. We installed a pre-programmed module just like this one, and the problem was solved instantly. It’s a common failure point I’ve seen dozens of times on these GM platforms.
Is Your Vehicle Showing These Red Flags?
A failing ECM can manifest in many ways. If you’re experiencing any of the following, it’s a strong indicator that your engine’s computer needs attention:
- ✔ Check Engine Light (CEL) is on with communication error codes (e.g., U0100) or internal module failure codes (e.g., P0601, P0606).
- ✔ Engine cranks but will not start.
- ✔ Unexplained drop in fuel mileage.
- ✔ Rough or erratic idle.
- ✔ Vehicle stalls unexpectedly while driving.
- ✔ Harsh or incorrect automatic transmission shifting.
- ✔ Failure to pass an emissions inspection.
A Straightforward Guide to Installation
Installing your new 2009 Envoy Engine Module is a job most DIYers can handle in their garage. No specialized programming tools are required.
- Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent accidental contact.
- Locate the ECM: On most of these vehicles, the ECM is mounted on the driver’s side of the engine or on the firewall. It’s a silver metal box with several large electrical connectors.
- Disconnect and Remove: Carefully unplug the wiring harness connectors. They have locking tabs that need to be released. Once disconnected, unbolt the old module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed module into place. Firmly reconnect the wiring harnesses, ensuring each plug is fully seated and the locking tabs click into place.
- Reconnect Power: Re-attach the negative battery terminal and tighten it securely.
- Final Step: It is often recommended to perform a security or idle relearn procedure, which can typically be done without a scan tool. A common method is to turn the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’ for 30 seconds, and repeat three times before starting the engine. Check your vehicle’s specific procedure for best results.
Verified Vehicle Compatibility
This module is a direct replacement for a wide range of GM vehicles and is interchangeable with multiple service numbers, including 12636659, 12639300, 1263605, 12628993, 12628911, 12625453, 12622175, 12630464, and 12678512. It is guaranteed to fit the following models with the specified options:
- Buick DTS: 2009-2011
- Buick Lucerne: 2009-2011 (4.6L, lower part of air cleaner box)
- Cadillac CTS: 2009 (6.2L, RH front engine compartment)
- Cadillac SRX: 2009 (4.6L, LH engine compartment)
- Cadillac STS: 2009 (4.4L or 4.6L, LH frame rail), 2010 (4.6L, LH frame rail)
- Cadillac XLR: 2009 (RH front engine compartment, ID 12636659 or 12625453)
- Chevrolet Colorado: 2009, 2010-2012 (2.9L or 3.7L, RH firewall)
- Chevrolet Corvette: 2009 (ZR1, RH engine compartment)
- Chevrolet Trailblazer: 2009 (6.0L, LH engine)
- GMC Canyon: 2009, 2010-2012 (2.9L or 3.7L, RH firewall)
- GMC Envoy: 2009 (5.3L, LH engine)
- Hummer H3: 2009, 2010 (3.7L, RH firewall)
- Saab 9-7X: 2009 (LH engine)