Restore Peak Performance to Your Vehicle’s Engine
Is your 2009 Cadillac SRX or other GM vehicle suffering from frustrating issues like intermittent stalling, a persistent Check Engine Light, rough idling, or a complete no-start condition? These are classic signs of a failing Engine Control Module (ECM), the computer that acts as the brain of your engine. When it falters, it can cause a cascade of problems that leave you stranded and facing a costly dealership repair. This replacement ECM, part number 12639300, is the reliable, straightforward solution to get your vehicle running smoothly again.
For over 20 years in the shop, I’ve seen how a faulty ECM can mimic a dozen other problems, leading to wasted time and money on unnecessary parts. That’s why we take the guesswork out of the equation. The single most critical part of this repair is the programming. We handle that for you. Before we ship your part, our technicians will flash this module with the very latest GM-certified software, specifically matched to your vehicle using the VIN you provide. This ensures perfect communication between your engine, transmission, and other onboard systems, restoring the original factory performance and efficiency.
From the Diagnostic Bay: The Ghost in the Machine
A customer brought in a 2009 Cadillac STS with a perplexing no-start condition. The battery was good, the starter cranked, and it had fuel pressure, but there was no spark and no injector pulse. The scanner was throwing a generic communication error (U0100) but also a P0606 (ECM Processor Fault). We checked all the wiring and grounds—they were perfect. Many technicians would start throwing parts at it. But based on experience, I know that internal processor faults are often a dead end. We connected a known-good test ECM, and the engine fired right up. The original ECM’s main processor had simply failed internally, a common issue caused by heat cycles and age. This is why a quality, correctly programmed replacement is non-negotiable.
Is Your Vehicle Showing These Symptoms?
- ✔ Unexplained Check Engine Light illumination
- ✔ Engine cranks but refuses to start
- ✔ Stalling for no apparent reason, either at idle or while driving
- ✔ Noticeable decrease in fuel economy
- ✔ Poor acceleration and overall sluggish performance
- ✔ Harsh or erratic automatic transmission shifting
- ✔ Common diagnostic trouble codes (DTCs) stored, such as P0601, P0606, or U0100
A Straightforward Guide to Installation
Replacing the 2009 SRX Engine Control Module is a job most DIYers with basic tools can handle. By receiving a pre-programmed unit, you skip the most difficult step.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait 10-15 minutes for the system capacitors to discharge.
- Locate the ECM: On the 2009 SRX, the ECM is found in the driver’s side front of the engine compartment. Its location varies on other models (see fitment list for clues). It’s a silver metal box with large electrical connectors.
- Disconnect Connectors: Carefully release the locking tabs on the wiring harness connectors and pull them straight out from the module. Never force them. Inspect the pins for any corrosion or damage.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket. Keep the hardware as you will reuse it.
- Install the New Module: Mount your new, pre-programmed ECM onto the bracket and secure it with the original bolts.
- Reconnect Everything: Firmly plug the wiring harnesses back into the new ECM until the locking tabs click into place. Reconnect the negative battery terminal.
- Final Steps: Your vehicle may require a security relearn procedure, which can typically be done without special tools by cycling the key. Consult your owner’s manual or a reliable online resource for the specific procedure for your vehicle. Once complete, start the engine and enjoy a smooth-running vehicle.
Verified Vehicle Compatibility
This ECM is a direct-fit replacement for a wide range of GM vehicles. It is interchangeable with service numbers 12636659, 12639300, 1263605, 12628993, 12628911, 12625453, 12622175, 12630464, and 12678512. Please confirm your vehicle is on this list:
- Cadillac CTS (2009) – 6.2L
- Cadillac DTS (2009-2011)
- Cadillac SRX (2009) – 4.6L
- Cadillac STS (2009) – 4.4L, 4.6L
- Cadillac STS (2010) – 4.6L
- Cadillac XLR (2009)
- Chevrolet Colorado (2009-2012) – 2.9L, 3.7L
- Chevrolet Corvette (2009) – ZR1
- Chevrolet Trailblazer (2009) – 6.0L
- GMC Canyon (2009-2012) – 2.9L, 3.7L
- GMC Envoy (2009) – 5.3L
- Hummer H3 (2009-2010) – 3.7L
- Buick Lucerne (2009-2011) – 4.6L
- Saab 9-7X (2009)
Frequently Asked Questions About This ECM
Do I need to do any programming myself?
Do I need to do any programming myself?
No. This is the biggest benefit of our service. We program the Engine Control Module using your car’s VIN before it ships. It arrives at your door ready for installation, saving you a trip to the dealer and expensive programming fees.
What information do you need from me?
Do I need to do any programming myself?
No. This is the biggest benefit of our service. We program the Engine Control Module using your car’s VIN before it ships. It arrives at your door ready for installation, saving you a trip to the dealer and expensive programming fees.
Is this a guaranteed fix for my vehicle’s problems?
Do I need to do any programming myself?
No. This is the biggest benefit of our service. We program the Engine Control Module using your car’s VIN before it ships. It arrives at your door ready for installation, saving you a trip to the dealer and expensive programming fees.
Will I need to perform a security relearn?
Do I need to do any programming myself?
No. This is the biggest benefit of our service. We program the Engine Control Module using your car’s VIN before it ships. It arrives at your door ready for installation, saving you a trip to the dealer and expensive programming fees.