Is Your GM Vehicle Running Rough, Stalling, or Showing a Check Engine Light?
The Engine Control Module (ECM), often called the engine computer, is the electronic brain of your vehicle. It manages everything from fuel injection and ignition timing to transmission shifts and emissions control. When it begins to fail, it can cause a cascade of confusing and frustrating problems that can be difficult to diagnose. You might experience intermittent stalling, poor fuel economy, a loss of power, or a persistent check engine light with codes that seem to point to other components. Don’t replace perfectly good sensors and parts chasing a ghost—the root cause is often a faulty ECM.
This is a direct-fit replacement Engine Control Module, part number 12678815, for a wide range of General Motors vehicles, including the 2017 Cadillac CTS, Chevrolet Silverado, GMC Sierra, and Cadillac Escalade. We take the guesswork out of the replacement process. Before we ship your part, we program it with the latest GM factory software using the Vehicle Identification Number (VIN) you provide. This ensures that the module is perfectly matched to your vehicle’s specific configuration, options, and emissions standards, restoring its original performance and reliability.
Common Symptoms of a Failing ECM
- ✔ Check Engine Light is on with various trouble codes (especially communication or internal processor codes like P0606).
- ✔ Vehicle experiences intermittent or constant no-start conditions.
- ✔ Noticeable decrease in fuel efficiency.
- ✔ Engine stalls, stumbles, or misfires unexpectedly.
- ✔ Rough or erratic automatic transmission shifting.
- ✔ Loss of power and poor acceleration.
- ✔ Communication issues with diagnostic scan tools.
From the Diagnostic Bay
We had a 2017 GMC Sierra 1500 in the shop that was driving the owner crazy. It would randomly stall at stoplights, but then start right back up. He had already replaced the fuel pump and a couple of sensors based on another shop’s advice, but the problem persisted. When we hooked up our diagnostic tools, we noticed intermittent communication drops with the engine computer. Instead of throwing more parts at it, we inspected the ECM. After confirming the power and grounds were solid, we knew the internal processor was failing. We installed a VIN-programmed ECM, performed the security relearn, and the truck ran perfectly. It’s a classic case where what seems like a fuel or sensor issue is actually the computer itself.
Why a Programmed 2017 CTS Engine Control Module is Essential
Modern vehicles are complex systems. An ECM from another vehicle, even an identical model, will not work correctly in yours. It needs to be coded with the specific software for your engine, transmission, and factory options. Our professional programming service handles this for you. By providing your VIN, you receive a module that is ready for the final installation steps, loaded with the most current calibrations from GM. This process corrects software bugs from the original release and ensures optimal engine performance and efficiency.
Installation and Required Relearn Procedures
Once you install the new ECM, there are a few final steps required to sync it with your vehicle. This is standard procedure for this type of repair. The most critical step is the Vehicle Theft Deterrent System (VTDS) relearn. If this is not performed, the vehicle’s security system will prevent the engine from starting. This procedure must be done on the vehicle using a GM-specific programming system like Tis2web or Techline Connect, which is typically available to professional repair shops and dealerships.
Additionally, other system relearns may be necessary depending on your vehicle’s specific needs, such as:
- Crankshaft Variation Relearn: To ensure accurate misfire detection.
- Injector Flow Rate Programming: To match the new computer to your existing fuel injectors.
- Other setup procedures as required by your vehicle.
Please Note: The buyer or their certified technician is responsible for performing these post-installation relearn and setup procedures. We provide a part that is correctly programmed to your VIN; the final vehicle integration must be completed by the installer.
Broad Compatibility Across the GM Lineup
This ECM, part number 12678815, is a service replacement for several other part numbers including 12692068, 12704476, 12686382, 12674052, and 12674472. It fits a wide variety of popular GM trucks and cars from 2016-2018. Please verify the part number or consult the fitment list to ensure this is the correct module for your vehicle.
Frequently Asked Questions
What is VIN programming?
VIN programming is the process of loading your vehicle’s specific software and calibration files onto the ECM. We use your unique 17-digit Vehicle Identification Number (VIN) to access the correct GM factory files, ensuring the module works perfectly with your engine, transmission, and options.
Is this part plug-and-play?
No. While our programming handles the software side, you must perform a security relearn procedure on the vehicle after installation. Without this step, the vehicle will not start. Other relearns, like for the crankshaft position sensor, may also be required.
Where do I find my VIN?
Your VIN can be found on a metal plate on the driver’s side dashboard (visible through the windshield), on the driver’s side door jamb sticker, or on your vehicle’s registration and insurance documents.
Can I perform the security relearn myself?
The security relearn requires access to GM’s professional diagnostic software (Tis2web/Techline Connect). While some advanced DIY mechanics may have access, it is typically performed by a qualified automotive technician or dealership.
Will this fix my specific check engine light code?
A faulty ECM can cause a wide range of diagnostic trouble codes. This module is a common solution for internal processor failure codes (e.g., P0601-P0606) and persistent communication errors. However, you should always have a proper diagnosis performed to confirm the ECM is the source of the problem before ordering.