Restore Peak Performance to Your GM Vehicle
If you’re dealing with frustrating and unpredictable issues like stalling, poor fuel economy, a persistent check engine light, or a vehicle that refuses to start, a failing Engine Control Module (ECM) is often the culprit. As the central computer of your vehicle, the ECM manages everything from fuel injection and ignition timing to transmission shifting. When it falters, the entire system suffers. This is a direct-fit, VIN-programmed replacement 2009-2010 STS Engine Module, designed to restore your vehicle’s reliability and performance without a costly trip to the dealership for programming.
Over my 20+ years in diagnostics, I’ve seen countless drivers spend a fortune chasing down sensor-related codes, only to find the root cause was a compromised ECM. Heat cycles, vibration, and age can cause internal components and solder joints to fail, leading to intermittent problems that are a nightmare to diagnose. This module solves that problem by providing a dependable, fully updated computer brain for your car or truck. We take your vehicle’s VIN, flash the module with the latest stable software from GM, and ship it directly to you, ready for installation.
Case Study: The Ghost in the Cadillac
A customer brought in a 2010 Cadillac DTS with an issue that was driving him crazy. It would randomly fail to start, but only after it was warm. No check engine light, no consistent codes. We checked the fuel pump, crank sensor, and battery—all were fine. On a hunch, I monitored the ECM’s data stream during a hot soak. I noticed the 5-volt reference signal to several key sensors would momentarily drop out just before the no-start condition. After swapping in a known-good, programmed ECM, the problem vanished. The original module had an internal thermal failure that only appeared under specific conditions. This is a classic example of how a failing ECM can mimic other problems, and why a quality replacement is key.
Is Your Vehicle Exhibiting These ECM Failure Signs?
A faulty ECM can manifest in numerous ways. If you’re experiencing any of the following, this module is the likely solution. Common diagnostic trouble codes (DTCs) associated with this failure include P0601, P0606, and U0100.
- ✔ Vehicle has intermittent or consistent no-start conditions.
- ✔ Check Engine Light is illuminated with communication-related codes.
- ✔ Noticeable drop in fuel efficiency.
- ✔ Engine stumbles, stalls, or hesitates during acceleration.
- ✔ Automatic transmission shifts erratically or harshly.
- ✔ Apparent loss of power and performance.
- ✔ Communication issues with diagnostic scan tools.
A Straightforward Guide to Installation
Installing your new 2009-2010 STS Engine Module is a manageable task for a DIYer with basic tools. Following these steps ensures a safe and successful replacement.
- Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent accidental reconnection.
- Locate the ECM: On the Cadillac STS, the ECM is typically located on the driver’s side frame rail. For other models, refer to the fitment list below for its general location (e.g., RH firewall, LH engine compartment).
- Disconnect Connectors: Carefully release the locking tabs on the electrical wiring harnesses and gently pull them straight out from the module. Do not force them. Inspect the connectors for any corrosion or damaged pins.
- Remove the Old Module: Unbolt the mounting hardware holding the old ECM in place. Keep the hardware, as you will reuse it for the new module.
- Install the New Module: Mount the new ECM using the original hardware. Ensure it is secure.
- Reconnect Everything: Firmly plug the wiring harnesses back into the new module until they click into place. Reconnect the negative battery terminal.
- Perform Relearn (If Necessary): While this module is pre-programmed, some vehicles may require a security or crank-sensor relearn procedure. In most cases, cycling the key from ‘Off’ to ‘On’ (without starting) a few times is sufficient. The vehicle is now ready to start.
Verified Vehicle Compatibility
This module, part number 1263605, is a direct replacement for a wide range of GM vehicles and is interchangeable with service numbers 12636659, 12639300, 12628993, 12628911, 12625453, 12622175, 12630464, and 12678512. Please confirm your model and engine below:
- ✔ 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): ID 12636659 or 12625453
- ✔ 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
Is this module truly plug-and-play?
Is this module truly plug-and-play?
Yes! We program the module to your vehicle’s specific VIN before shipping. This means you do not need to take it to a dealer for programming. In some rare cases, a simple security relearn procedure (often just cycling the key) may be needed, which requires no special tools.
Where do I provide my VIN?
Please enter your 17-digit Vehicle Identification Number (VIN) in the designated box on the checkout page. We cannot process your order without it, as the programming is essential for the part to function correctly.
Will this fix my specific check engine light code?
This module is the definitive solution for internal processor failure codes like P0601 or P0606, as well as communication loss codes like U0100. While it can resolve issues causing other codes, you should ensure your vehicle’s sensors and wiring are in good condition first.
Is this a new or used part?
This is a high-quality, inspected, and tested recycled OEM part. Each unit is verified to be fully functional before being programmed with the latest GM software for your vehicle, ensuring OEM-level performance and reliability.
What if my original part number isn’t 1263605?
That’s okay. GM uses many interchangeable service numbers. This module is a direct replacement for several part numbers, including 12636659, 12639300, 12628993, and others listed in the description. As long as your vehicle is on the compatibility list, this module will work.