Is Your Envoy Running Rough, Stalling, or Showing a Check Engine Light?
As a technician with over two decades of experience, I’ve seen countless GM vehicles come into the shop with frustrating and often intermittent issues. A faulty Engine Control Module (ECM) is frequently the culprit behind problems that seem to have no other explanation—from poor fuel economy and hesitation to a complete no-start condition. If you’re dealing with these headaches in your 2009 GMC Envoy, you’ve found the reliable, straightforward solution.
This isn’t just a replacement part; it’s a complete fix. We are providing a genuine GM Engine Control Module, part number 12678512, that comes fully programmed to your vehicle’s specific Vehicle Identification Number (VIN). This critical step ensures that all systems communicate correctly, just as the factory intended. We load the latest, most stable software updates from GM, which often resolve underlying drivability issues that older software versions had. You get a part that is truly ready to install right out of the box.
Real-World Diagnosis Story: “A customer’s 2009 Trailblazer with the 6.0L—which uses this exact same ECM—came into my bay last week with a persistent P0606 code (ECM/PCM Processor Fault) and an intermittent hard start. We checked all the basics: battery, grounds, and wiring harnesses, and everything looked perfect. After swapping in one of our pre-programmed modules, the code vanished, and the truck fired up instantly every time. The original ECM had an internal processor failure that only showed up under specific conditions, a common failure mode for these units after years of heat cycles.”
Why Our Programmed 2009 Envoy Engine Module is the Smart Choice
- ✔ VIN-Specific Programming Included: We flash the module with the latest GM software using your vehicle’s VIN. This eliminates the need for an expensive trip to the dealership for programming.
- ✔ Solves Common Failure Symptoms: An effective solution for check engine lights, communication error codes, stalling, rough idling, poor acceleration, and no-start scenarios.
- ✔ Direct-Fit Replacement: Guaranteed to be compatible with a wide range of GM vehicles, ensuring a perfect fit and proper function.
- ✔ Restores Peak Performance: A correctly functioning ECM is essential for optimal engine performance, fuel efficiency, and emissions control.
Plug-and-Play Installation: No Dealer Visit Required
Installing your new ECM is a job most DIYers can handle. While specific steps may vary slightly by model, here is a general guide for a 2009 Envoy:
- Safety First: Always disconnect the negative battery terminal and wait a few minutes for the system to discharge completely.
- Locate the ECM: On the 2009 Envoy with the 5.3L engine, the ECM is typically located on the driver’s side of the engine bay, near the air filter housing.
- Disconnect Connectors: Carefully release the locking tabs on the electrical connectors and pull them straight out. Never force them. Inspect the pins for any corrosion or damage.
- Remove the Old Module: Unbolt the mounting brackets holding the old ECM in place and remove it from the vehicle.
- Install the New Module: Mount your new, pre-programmed 2009 Envoy Engine Module in the same location, secure the bolts, and firmly reconnect the electrical connectors until they click into place.
- Final Steps: Reconnect the negative battery terminal. The vehicle may need to complete a security relearn procedure, which can often be done by cycling the key. Your vehicle is now ready to start.
Guaranteed Compatibility & Cross-Reference
This module is a direct replacement for several GM service numbers. If your original module has any of the following numbers, this part is a 100% compatible replacement: 12636659, 12639300, 1263605, 12628993, 12628911, 12625453, 12622175, 12630464, and 12678512.
Extensive Vehicle Fitment List:
This versatile ECM fits a wide array of GM vehicles, including:
- Cadillac: CTS (2009), DTS (2009-11), SRX (2009), STS (2009-10), XLR (2009)
- Chevrolet: Colorado (2009-12), Corvette (2009), Trailblazer (2009)
- GMC: Canyon (2009-12), Envoy (2009)
- Hummer: H3 (2009-10)
- Buick: Lucerne (2009-11)
- Saab: 9-7x (2009)
Please provide your VIN during checkout to ensure we can program the module for your specific vehicle before shipping.