Restore Peak Performance to Your GM Truck or Car
If you’re dealing with frustrating engine problems 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 a technician with over 20 years of experience, I’ve seen how a faulty ECM can create a cascade of baffling issues. This isn’t just a part; it’s the brain of your engine, and when it’s not working right, nothing is. This replacement ECM is your direct, reliable solution to get your vehicle running smoothly again.
This module, part number 12663391, is a genuine GM component that we program specifically for your vehicle using your VIN. This critical step ensures that all factory settings, security protocols (like anti-theft), and operational parameters are perfectly matched to your truck or car. By programming it before shipment with the latest GM software updates, we eliminate the need for an expensive trip to the dealership. You get a component that’s ready for installation right out of the box.
A Technician’s Notebook: The Ghost in the Machine
I remember a 2015 Silverado 1500 that came into my shop with a problem that had stumped two other mechanics. The owner complained of random stalling at stoplights and occasional hard starting. There were no consistent trouble codes, just a sporadic U0100 (Lost Communication with ECM) that would appear and vanish. We checked the wiring, grounds, and connectors—all seemed perfect. On a hunch, I put a scope on the CAN bus network. I noticed that the ECM’s signal would occasionally drop out for a millisecond, just long enough to cause a hiccup but not always long enough to set a hard fault. It was an internal failure of the processor. We replaced the ECM with a VIN-programmed unit like this one, and the truck ran perfectly. It’s a classic example of how a failing 2014-2016 Sierra Denali ECM can manifest as an intermittent, hard-to-diagnose issue.
Is Your GM Vehicle Showing These Symptoms?
- ✔ Check Engine Light is on with codes pointing to the module itself (e.g., P0601, P0606).
- ✔ Your vehicle won’t start, and you’ve ruled out the battery and starter.
- ✔ Unexplained loss of engine power or sudden stalling.
- ✔ Poor or erratic automatic transmission shifting.
- ✔ Communication errors with your scan tool or other modules (U-codes).
- ✔ Noticeable decrease in fuel efficiency.
- ✔ The anti-theft or security light stays on, preventing the engine from starting.
A Straightforward Guide to Installation
Replacing the ECM is a task many DIYers can handle. Since we program the module for you, no special tools are needed for software setup. For a 2014-2016 Sierra Denali 1500, the 2014-2016 Sierra Denali ECM is typically located in the front left of the engine compartment. Always consult a service manual for your specific model’s location.
- 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: Find the module in your engine bay. It’s a metal box with several large electrical connectors.
- Disconnect the Connectors: Carefully release the locking tabs on each wiring harness connector and pull them straight out. Avoid pulling on the wires themselves.
- Remove the Old Module: Unbolt the mounting hardware that holds the old ECM in place and remove it from the vehicle.
- Install the New Module: Mount your new, pre-programmed ECM in the same location and secure it with the original hardware.
- Reconnect Everything: Firmly plug the wiring harnesses back into the new ECM until they click into place. Reconnect your negative battery terminal.
- Final Check: Turn the key to the ‘On’ position for 10-15 seconds before starting the engine. This allows the other modules to recognize the new ECM. Start your vehicle and check for proper operation.
Verified Vehicle Compatibility
This ECM is a direct replacement for part number 12663391 and is also compatible with part numbers: 12692067, 12676230, 12656993, 12662034, 12672537, 12673195, 12672963, and 12669318. It fits a wide range of GM vehicles, including:
- ATS (2014-2016)
- CAMARO (2016)
- CANYON (2015-2016)
- COLORADO (2015-2016)
- CORVETTE (2014-2016)
- CTS (2014-2016)
- ESCALADE & ESCALADE ESV (2015-2016)
- SIERRA 1500 PICKUP & SIERRA DENALI 1500 (2014-2016)
- SILVERADO 1500 PICKUP (2014-2016)
- SUBURBAN 1500 (2015-2016)
- TAHOE (2015-2016)
- YUKON & YUKON XL 1500 (2015-2016)
- XTS (2014-2016)
Please verify your specific model and options from the detailed fitment list or contact us with your VIN to confirm compatibility.
Frequently Asked Questions
What is VIN programming and why is it necessary?
VIN programming is the process of loading your vehicle’s unique 17-digit Vehicle Identification Number (VIN) and its associated software into the ECM. This ensures the module works with your specific engine, transmission, and options, including the anti-theft system. Without it, the vehicle will not start or run correctly. We handle this for you before shipping.
Do I need to do anything else after I install this ECM?
No. Because we program the module to your VIN, it is a plug-and-play installation. In some rare cases, a specific procedure like a crankshaft position sensor relearn may be needed, which can be done with many high-level scan tools, but typically no further action is required.
How do I provide my VIN?
After you complete your purchase, you will need to send us a message with your vehicle’s 17-digit VIN. We cannot program and ship your module without it. You can find your VIN on your vehicle’s dashboard (visible through the windshield) or on your registration and insurance documents.
Is this a used or a new part?
This is a high-quality, tested, and guaranteed functional OEM component. Each module is thoroughly inspected and then programmed with the latest software from GM to ensure reliability and performance that meets or exceeds the original factory standard.
What if my original part number is not on the compatibility list?
The listed part numbers are the most common interchanges. If your part number is different, please contact us with your VIN and original part number. GM often supersedes part numbers, and we can verify if this module is the correct, updated replacement for yours.