Restore Peak Performance to Your GM Vehicle
Is your Cadillac, Chevrolet, or GMC plagued by baffling issues like intermittent stalling, a persistent check engine light, or a complete no-start condition? Before you spend a fortune at the dealership, consider the heart of your vehicle’s engine management system: the Engine Control Module (ECM). As a technician with over 20 years of experience, I’ve seen firsthand how a failing ECM can mimic a dozen other problems. This isn’t just a part; it’s the solution to restoring your vehicle’s reliability and drivability.
This is a direct-fit replacement 2017 XTS Engine Control Module, also known by part number 12678815. The real value here is our professional programming service. We flash the module with the latest GM-certified software, specifically matched to your vehicle’s VIN. This means you receive a part that’s ready for the final, on-vehicle setup, saving you the time, expense, and hassle of towing your car to a service center for programming.
From the Diagnostic Bay: The Ghost in the Machine
I remember a 2017 Sierra 1500 that came into the shop with a laundry list of complaints from the owner: random stalling at red lights, poor acceleration, and a check engine light that three other shops couldn’t solve. They had replaced sensors and even a fuel pump. After hooking up my diagnostic scanner, I saw a few network communication codes but the smoking gun was a P0606 (ECM Processor Fault). The internal processor of the original ECM was failing intermittently, causing it to send corrupted data to other modules. We installed a VIN-programmed ECM just like this one, performed the crankshaft variation and theft relearns, and the truck ran like it just rolled off the factory floor. It’s a perfect example of how the right part, properly prepared, can solve a complex problem efficiently.
Is Your Vehicle Showing These Symptoms?
- ✔ Engine cranks but refuses to start.
- ✔ Unexplained stalling or rough idling.
- ✔ Noticeable decrease in fuel efficiency.
- ✔ Check Engine Light is on with codes like P0601, P0602, P0606, or U0100.
- ✔ Transmission shifting erratically or harshly.
- ✔ Apparent loss of power and poor acceleration.
A Straightforward Guide to Installation
- ✔ Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- ✔ Locate the ECM: On most of these GM trucks and SUVs, the ECM is found in the engine compartment, typically on the driver’s side. On cars like the Corvette or XTS, its location can vary (e.g., cowl area), so consult a service manual if you’re unsure.
- ✔ Disconnect and Remove: Carefully unplug the wiring harness connectors. They have locking tabs that need to be released. Once disconnected, unbolt the old module from its mounting bracket.
- ✔ Install the New Module: Mount your new, pre-programmed ECM and securely reconnect the wiring harnesses. Ensure they click into place.
- ✔ Reconnect Battery: Reattach the negative battery terminal.
- ✔ Perform Relearn Procedures: This is a critical final step. The vehicle will likely not start until a Vehicle Theft Deterrent (VTD) relearn is completed using a GM-compatible diagnostic tool (like TIS2Web or Techline Connect). Other procedures, such as a crankshaft position sensor variation relearn, may also be required for optimal performance. This is the responsibility of the installer.
Will This Fit My Vehicle?
This module is a confirmed fit for a wide range of GM vehicles. Please verify your part number or match your vehicle from the list below. This part replaces numbers 12692068, 12704476, 12686382, 12674052, 12674472, and 12678815.
- Cadillac ATS (2017): 3.6L, VIN Y (LF4)
- Cadillac CTS (2017): 6.2L (Supercharged) or 3.6L, VIN 8 (LF3, Twin Turbo)
- Cadillac Escalade / ESV (2017)
- Cadillac XTS (2017): 3.6L, VIN 8 (LF3)
- Chevrolet Corvette (2017)
- Chevrolet Silverado 1500 (2016-2018)
- Chevrolet Suburban 1500 (2017)
- Chevrolet Tahoe (2017)
- GMC Sierra 1500 / Denali 1500 (2016-2018)
- GMC Yukon / Yukon XL 1500 (2017)
Frequently Asked Questions About This 2017 XTS Engine Control Module
Frequently Asked Questions
What do I need to do after I purchase?
After you complete your purchase, you must provide us with your vehicle’s 17-digit Vehicle Identification Number (VIN). We use this to load the correct, updated GM software for your specific vehicle before we ship the part to you.
Why won’t my car start after installing the new ECM?
This is almost always due to the vehicle’s anti-theft system. A Vehicle Theft Deterrent (VTD) relearn procedure must be performed using a professional scan tool with GM software (like TIS2Web/Techline Connect). This security handshake pairs the new ECM to your vehicle.
Is this part truly “plug-and-play”?
It’s as close as it gets. The module is pre-programmed, which handles the most difficult part. However, the final on-vehicle security relearn and potentially other minor setup procedures (like for the crankshaft sensor) are required for the installation to be complete. This is standard for all modern ECM replacements.
Can a DIY mechanic install this?
A mechanically inclined DIYer can certainly handle the physical swap. However, you will need access to a high-level, GM-compatible scan tool to perform the necessary final relearn procedures. If you don’t have this equipment, you will need assistance from a professional mechanic for the final step.
How do I confirm this is the right part number for me?
The best way is to check the part number on the label of your original ECM. This module, 12678815, also replaces several other part numbers listed in our description. Matching your vehicle, year, and model in our fitment list is also a reliable method.