Restore Your Vehicle’s Core Command Center
Is your Cadillac ELR, Chevy Cruze, or Silverado exhibiting strange behavior? Frustrating issues like stalling, a persistent check engine light, or a complete no-start condition often point to a single culprit: a failing Engine Control Module (ECM). As a technician with over two decades of experience, I’ve seen firsthand how a faulty ECM can cripple a perfectly good vehicle. It’s the brain of your engine, and when it malfunctions, the entire system suffers. This isn’t just an inconvenience; it’s a reliability issue that can leave you stranded.
This isn’t just a replacement part; it’s a direct solution. We offer a genuine GM Engine Control Module, part number 12668866, that arrives at your door pre-programmed with the latest GM software updates specific to your vehicle’s VIN. This critical step eliminates the need for expensive dealership programming or specialized scan tools, saving you significant time and money. By providing us with your VIN during checkout, you ensure that this module is ready for installation right out of the box, restoring the precise performance and communication protocols your vehicle was designed with.
Common Signs of a Failing ECM
- âś” Unexplained check engine light that won’t clear.
- âś” Engine stalling, misfiring, or running rough for no apparent reason.
- âś” Complete no-start condition where the engine cranks but won’t fire up.
- âś” Noticeable decrease in fuel economy.
- âś” Transmission shifting problems or harsh engagement.
- âś” Communication error codes, such as U0100 (Lost Communication With ECM/PCM).
- âś” Internal module failure codes, like P0601, P0603, or P0606.
Case Study: A Tricky Diagnosis
A customer brought in a 2015 Chevy Volt—a cousin to the ELR—with an intermittent no-start problem. The battery was fine, the starter engaged, but the engine wouldn’t fire. There were no consistent trouble codes, just a random U0100 communication code that would appear and disappear. After hours of checking wiring harnesses and grounds, we hooked up a scope to the CAN bus lines at the ECM connector. We found the data signal would simply drop out when the fault occurred. Swapping in a known-good, programmed ECM like this one immediately solved the problem. The original module’s internal processor was failing under certain temperature conditions, a classic sign of electronic fatigue that a simple code reader can’t always pinpoint.
A Straightforward Guide to Installation
- âś” Safety First: Disconnect the negative terminal from your vehicle’s 12V battery and secure it away from the post to prevent accidental contact.
- âś” Locate the ECM: On the 2014-2016 ELR, the ECM is found in the left-hand (driver’s side) rear of the engine compartment. For other models like a Silverado, it’s typically on the LH front of the engine bay. Always consult a service manual for your specific vehicle’s location.
- âś” Disconnect Connectors: Carefully release the locking tabs on the electrical connectors and pull them straight out from the module. Never force them. Inspect the pins for any corrosion or damage.
- âś” Remove the Old Module: Unbolt the mounting hardware holding the old ECM in place and remove it from the vehicle.
- âś” Install the New Module: Mount your new, pre-programmed ECM and secure it with the original hardware.
- âś” Reconnect Everything: Plug the electrical connectors back into the new module until they click securely into place. Reconnect the negative battery terminal.
- âś” Perform Relearn (If Necessary): While this module is programmed, some vehicles require a security or crank position sensor relearn procedure. This can often be done without a scan tool (e.g., by cycling the key). Check your vehicle’s specific requirements.
Verified Vehicle Compatibility
This ECM, part number 12668866, is a direct replacement for a wide range of General Motors vehicles. It supersedes several older part numbers, including 12668994, 12643636, and 12670335. While it is the correct module for the 2014-2016 ELR Engine Control Module, it also fits many other popular models. Please use the compatibility list and match your original part number to ensure a perfect fit. Key compatible models include:
- Cadillac ELR (2014-2016)
- Chevrolet Cruze (2012-2016)
- Chevrolet Sonic (2012-2016)
- Chevrolet Volt (2011-2015)
- Chevrolet Silverado 2500/3500 (2012-2016, 6.0L)
- GMC Sierra 2500/3500 (2012-2016, 6.0L)
- Buick Encore (2013-2016)
- Chevrolet Express / GMC Savana Vans (2016)
Frequently Asked Questions
Do I need to do any programming myself?
No. We handle all the programming before shipping. We use the VIN you provide to flash the module with the latest, vehicle-specific software from GM. It arrives ready to be installed.
Is this a new or used part?
This is a high-quality, tested, and verified genuine GM part that has been professionally programmed to function as a reliable replacement for your original failed module.
How do I find my vehicle’s VIN?
Your 17-digit Vehicle Identification Number (VIN) can be found on your vehicle’s registration, insurance card, or on a plate on the driver’s side dashboard visible through the windshield.
What if I have other part numbers like 12643636 or 12668994?
This module, 12668866, is the correct and updated service replacement for those part numbers and others listed. It is fully compatible and contains the most current software.
Will this fix my check engine light?
If the check engine light is caused by an internal failure of the ECM (like codes P0601-P0606), then yes, this will resolve the issue. However, you must ensure all other potential problems (sensors, wiring, etc.) have been properly diagnosed and fixed first.