Restore Peak Performance to Your High-Output GM Vehicle
Is your 2017 Cadillac ATS, CTS V-Sport, or another high-performance GM vehicle suddenly plagued by frustrating issues like a no-start condition, intermittent stalling, or a persistent Check Engine Light? As a technician with over two decades of experience, I’ve seen how a failing Engine Control Module (ECM) can sideline even the most powerful cars and trucks. The ECM is the brain of your engine, and when it falters, everything from fuel delivery to spark timing is compromised. This isn’t just an inconvenience; it’s a critical failure that needs a reliable solution.
This genuine GM Engine Control Module, part number 12678815, is the definitive fix. We take the guesswork and hassle out of the replacement process. Before this module ships, we will program it with the latest official GM software, precisely matched to your vehicle’s specific VIN. This crucial step ensures that all factory calibrations are correct, saving you a costly trip to the dealership and the need for expensive programming equipment. You get a component that’s ready for the final onboard learning procedures, getting you back on the road with confidence.
A Technician’s Notebook: The Intermittent No-Start ATS
A few months back, a 2017 Cadillac ATS with the potent 3.6L twin-turbo LF4 engine was towed into my bay. The owner was at his wit’s end. The car would run perfectly for days, then refuse to start, with no crank and a flurry of communication error codes on the dash. We checked the battery, grounds, and starter circuit—all perfect. On a hunch, I monitored the ECM’s internal temperature data. I’ve learned that heat cycles can expose failing internal processors. Sure enough, after a long drive, the ECM would fail to initialize on the next key cycle. We replaced it with a VIN-programmed module just like this one, performed the VTD relearn, and the problem was solved for good. It’s often these subtle electronic failures that cause the biggest headaches.
Is Your Vehicle Showing These Common ECM Failure Symptoms?
- ✔ Unexplained no-start or no-crank conditions.
- ✔ The engine stalls unexpectedly while driving or at idle.
- ✔ A persistent Check Engine Light (CEL) that won’t clear.
- ✔ Diagnostic Trouble Codes (DTCs) related to internal processor failure, such as P0601, P0606, or P062B.
- ✔ Noticeable loss of power, poor acceleration, or decreased fuel economy.
- ✔ Communication errors with other vehicle modules (e.g., U0100 – Lost Communication With ECM/PCM).
- ✔ Erratic transmission shifting or other strange electronic behavior.
A Straightforward Guide to Installation
- ✔ Safety First: Always disconnect the negative terminal from your vehicle’s battery before beginning any electronic component replacement.
- ✔ Locate the ECM: On the 2017 ATS, the ECM is typically found in the left-hand (driver’s side) of the engine compartment. For other models, its location may vary (e.g., RH cowl on a Corvette). Consult a service manual if you’re unsure.
- ✔ Disconnect and Remove: Carefully unplug the electrical connectors. They have locking tabs that must be released. Once disconnected, unbolt the old module from its mounting bracket.
- ✔ Install the New Module: Bolt your new, pre-programmed ECM into place. Reconnect the electrical connectors, ensuring they click securely into position.
- ✔ Reconnect the Battery: Reattach the negative battery terminal.
- ✔ CRITICAL – Perform Relearns: This is the most important step. If the vehicle does not start, you MUST perform a Vehicle Theft Deterrent (VTD) relearn using a compatible GM diagnostic tool (like Tis2web or Techline Connect). Other procedures, such as a Crankshaft Variation Relearn, may also be required to ensure optimal performance and clear any related trouble codes. This is the responsibility of the installer.
Will This Fit My Vehicle? Verified Compatibility
This ECM is a direct replacement for part number 12678815 and is also compatible with part numbers 12692068, 12704476, 12686382, 12674052, and 12674472. It fits a wide range of GM models, including:
- Cadillac ATS: 2017 (3.6L, VIN Y, LF4)
- Cadillac CTS: 2017 (6.2L Supercharged or 3.6L Twin Turbo LF3)
- Cadillac Escalade / ESV: 2017
- Cadillac XTS: 2017 (3.6L, VIN 8, LF3)
- Chevrolet Corvette: 2017
- Chevrolet Silverado 1500: 2016 (ID 12674472), 2017, 2018 (ID 12686382)
- Chevrolet Suburban 1500: 2017
- Chevrolet Tahoe: 2017
- GMC Sierra 1500 / Denali 1500: 2016 (ID 12674472), 2017, 2018 (ID 12686382)
- GMC Yukon / Yukon XL 1500: 2017
Frequently Asked Questions
How do I provide my VIN for programming?
After you complete your purchase, please send us a message with your vehicle’s 17-digit VIN. We cannot program and ship your module without this information.
What is a Vehicle Theft Deterrent (VTD) relearn?
It’s a security procedure that syncs your new ECM to your vehicle’s ignition key and security system. Without it, the vehicle’s anti-theft system will prevent the engine from starting. This requires a professional scan tool with GM software access.
Can I perform the VTD relearn myself?
Unless you are a professional technician with access to GM’s Tis2web or Techline Connect software, you will likely need to have a qualified mechanic or dealership perform this final step for you after installation.
Is this a plug-and-play part?
It is ‘plug-in-and-program’. The module is pre-programmed to your VIN, which handles the complex software calibration. However, the final security relearn must be performed on the vehicle.
What if my vehicle has other issues?
This ECM will fix problems directly caused by a faulty module. It’s essential to ensure your vehicle’s underlying issues (e.g., bad sensors, wiring shorts) have been properly diagnosed and repaired first.