Restore Your Vehicle’s Core Performance and Reliability
Is your Cadillac, Chevy, or GMC acting erratically? A failing Engine Control Module (ECM) is often the culprit behind a host of frustrating issues, from a persistent check engine light and poor fuel economy to a dreaded no-start condition. In my 20+ years of diagnostics, I’ve seen how a faulty ECM can mimic dozens of other problems, leading to wasted time and money on unnecessary repairs. This isn’t just a component; it’s the brain of your engine, and when it falters, the entire vehicle suffers.
We offer a dependable solution: a genuine GM Engine Control Module, part number 12678815, delivered to your door already programmed to your vehicle’s specific Vehicle Identification Number (VIN). Forget the expensive dealership visit and towing fees. Simply provide us with your VIN at checkout, and our experts will flash the module with the latest, most stable software from General Motors. This ensures perfect communication between your engine, transmission, and other onboard systems, restoring the smooth, reliable performance you expect from your vehicle.
Case Study: The Ghost in the Machine
A customer brought in a 2017 Sierra 1500 with a bizarre issue: it would randomly stall at stoplights, but never threw a consistent code. We checked the fuel pump, sensors, and wiring—everything looked fine. After days of chasing phantom problems, we hooked up a scope to the ECM’s main processor. We found intermittent voltage drops that didn’t trigger a specific DTC but were just enough to shut down the engine. A new, correctly programmed ECM like this one solved the problem instantly. It’s a classic example of how a failing computer can create symptoms that lead you everywhere but the real source.
Is Your GM Vehicle Exhibiting These ECM Failure Signs?
A failing computer can manifest in numerous ways. If you’re experiencing any of the following, a faulty 2017 CTS Engine Control Module could be the cause. This module is also the correct fix for many other GM models showing these symptoms:
- ✔ Check Engine Light is on with communication-related codes (e.g., U0100, P0601, P0606).
- ✔ The engine cranks but refuses to start.
- ✔ Noticeable drop in fuel efficiency for no apparent reason.
- ✔ The engine is stalling, stumbling, or hesitating during acceleration.
- ✔ Automatic transmission shifts erratically or harshly.
- ✔ Apparent loss of power despite the engine sounding normal.
- ✔ Issues with other electronic systems, as the ECM is a central communication hub.
A Straightforward Guide to Installation
Replacing your ECM is a manageable job for a confident DIYer or any professional technician. With our pre-programmed module, you’re already 90% of the way there. Follow these general steps for a successful installation:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 15 minutes for capacitors to discharge.
- Locate the ECM: On most listed vehicles, the ECM is found in the engine compartment (often on the driver’s or passenger’s side) or under the cowl. Consult a vehicle-specific repair manual if you are unsure.
- Disconnect and Remove: Carefully unplug the wiring harness connectors. They have locking tabs that must be released. Then, unbolt the old module from its mounting bracket.
- Install the New Module: Bolt your new, pre-programmed ECM into place. Reconnect the wiring harnesses, ensuring they click securely into position.
- Reconnect the Battery: Reattach the negative battery terminal.
- Perform Security Relearn: This is the most critical final 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). This pairs the new ECM to your vehicle’s security system.
- Additional Setups: Depending on your vehicle, you may also need to perform other procedures like a Crankshaft Variation Relearn or injector flow rate programming. This is the responsibility of the installer.
Verified Vehicle Compatibility
This module is a direct replacement for part number 12678815 and also supersedes several other numbers, including 12692068, 12704476, 12686382, 12674052, and 12674472. It is guaranteed to fit the following makes and models:
- Cadillac ATS (2017): 3.6L (VIN Y, opt LF4)
- Cadillac CTS (2017): 3.6L Twin Turbo (VIN 8, opt LF3), 6.2L Supercharged
- Cadillac Escalade / ESV (2017)
- Cadillac XTS (2017): 3.6L (VIN 8, opt 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
What does ‘VIN Programmed’ mean?
It means we load the module with the specific software and calibrations for your exact vehicle using your VIN. This ensures it works correctly out of the box, saving you a trip to the dealer for programming.
Will this fix my check engine light?
If the check engine light is caused by an internal failure of the original ECM (e.g., codes P0601-P0606), then yes, this part is the correct fix. It’s crucial to properly diagnose the issue first, as the light can be triggered by many other components.
What is the ‘Theft Relearn’ and can I do it myself?
The theft relearn procedure syncs the new ECM with your vehicle’s anti-theft system. It is a mandatory step if the vehicle doesn’t start after installation. It requires a professional GM diagnostic tool like Techline Connect. Many mobile mechanics and most repair shops can perform this service for you.
Is this a brand new part?
This is a high-quality, tested, and verified OEM part that has been expertly programmed with the latest GM software for your vehicle. It’s a reliable and cost-effective alternative to a new dealership part.
How do I provide my VIN?
After you complete your purchase, you will need to send us your 17-digit Vehicle Identification Number (VIN). We cannot program and ship your module without it.