Restore Your Truck’s Brain and Brawn
The Engine Control Module (ECM), often called the Powertrain Control Module (PCM), is the central computer of your 2012-2016 GMC Sierra Denali 3500. It’s responsible for managing everything from fuel injection and ignition timing to transmission shifting and emissions control. When it begins to fail, it can cause a cascade of confusing and frustrating problems that can sideline your powerful truck. From a simple check engine light to a complete no-start condition, a faulty ECM can mimic a dozen other mechanical issues, making diagnosis a challenge.
This replacement Engine Control Module, part number 12670335, is the definitive solution to get your truck operating to factory specifications. We eliminate the guesswork and the expensive trip to the dealership by pre-programming the module specifically for your vehicle using your VIN. This ensures that all systems, options, and parameters are perfectly matched to your truck’s original build, providing a seamless and effective repair.
From the Diagnostic Bay
We had a 2014 Silverado 2500 (which uses the same ECM) come into the shop with a bizarre issue. The owner complained of random stalling, but only after driving for about 30 minutes. We checked everything—fuel pressure, sensors, wiring—and couldn’t find a fault. No codes were stored. On a hunch, we monitored the ECM’s internal temperature data. We found that as the module heated up in the engine bay, its processor would start to fail, causing the stall. Replacing the ECM with a correctly programmed unit solved the problem completely. It’s a classic case of how a failing computer can create phantom mechanical issues that seem impossible to trace.
Is Your Sierra 3500 Showing Signs of ECM Failure?
A failing ECM doesn’t always result in a total breakdown. Often, the symptoms start small and grow worse over time. If you’re experiencing any of the following, your ECM could be the culprit:
- ✔ Unexplained Check Engine Light (CEL) that won’t clear or returns intermittently.
- ✔ Poor engine performance, including hesitation, sputtering, or a noticeable loss of power.
- ✔ A significant and sudden decrease in fuel economy.
- ✔ Rough or erratic idling that you can’t trace to spark plugs or vacuum leaks.
- ✔ Harsh or incorrect transmission shifting patterns.
- ✔ The engine cranks but refuses to start.
- ✔ Communication errors when trying to use a diagnostic scan tool.
The Direct Solution: A VIN-Programmed 2012-2016 Sierra 3500 ECM
Don’t settle for a generic, one-size-fits-all module. Our process ensures precision and reliability. When you place your order, you provide us with your vehicle’s 17-digit VIN. We use this to connect directly to GM’s database and download the latest, most stable software calibration specifically for your truck. This accounts for your engine type (6.0L), transmission, emissions equipment, and any other factory-installed options. This VIN-specific programming is critical for proper vehicle function and is a service that dealerships often charge hundreds of dollars for. This module is a direct replacement for multiple part numbers, including 12668866, 12668994, 12643636, and more, ensuring wide compatibility.
Installation and Setup
Physically installing the module is straightforward for anyone with basic mechanical skills. After disconnecting the battery, you simply locate the old ECM in the engine compartment, unplug the harnesses, unbolt it, and install the new one in its place. While the module arrives programmed for your engine and systems, you will need to perform a simple security relearn procedure. This syncs the new ECM with your truck’s anti-theft system and keys. This procedure typically does not require special tools and we can provide easy-to-follow instructions.
Frequently Asked Questions
Do I need to take this ECM to a dealer for programming?
No. We handle all the programming for you before the part is shipped. Simply provide your vehicle’s VIN during checkout, and it will arrive ready for installation and a security relearn.
What is a VIN and why do you need it?
The VIN (Vehicle Identification Number) is a unique 17-digit code for your truck. It allows us to access the exact factory software and calibrations your vehicle was built with, ensuring a perfect software match.
Is this a simple plug-and-play installation?
It’s very close. After plugging the module in, you will need to perform a security relearn procedure to sync the module with your vehicle’s anti-theft system. This is a simple process that we provide instructions for.
How can I be sure my old ECM is the problem?
While the symptoms listed are strong indicators of a faulty ECM, a definitive diagnosis from a qualified technician using professional scan tools is the best way to be 100% certain before ordering.
Will this fix my check engine light?
If the check engine light and associated codes are being caused by an internal failure of the ECM, this replacement part will resolve the issue. Always clear any stored codes after installation.
Does this module fit other vehicles besides the Sierra 3500?
Yes. This versatile ECM was used in a wide range of GM vehicles, including the Silverado 2500/3500, Express/Savana vans, Chevy Cruze, Sonic, Trax, and Buick Encore. We program it specifically for the vehicle you provide the VIN for.