Restore Your Vehicle’s Core Performance and Reliability
Is your Cadillac ELR, Chevy Cruze, or Silverado experiencing baffling issues like a no-start condition, erratic engine behavior, or a persistent Check Engine Light? As a technician with over two decades of experience, I’ve seen firsthand how a failing Engine Control Module (ECM) can bring a perfectly good vehicle to a dead stop. This isn’t just a part; it’s the central command center for your engine’s performance, fuel delivery, and emissions. When it fails, the symptoms can be frustrating and difficult to diagnose, often leading to costly, unnecessary repairs.
This replacement Engine Control Module, part number 12668991, is the definitive solution. We take the guesswork and hassle out of the repair by pre-programming the unit specifically for your vehicle using your VIN. This means it arrives at your door with the latest GM software updates already installed, ready for a straightforward installation. You get a reliable fix that restores factory operation without the need for an expensive trip to the dealership for programming. This is the same process we use in the shop to get our customers back on the road quickly and confidently.
Case Study: The Intermittent Stall on a 2015 Volt
A customer brought in a 2015 Chevy Volt (which uses a similar system to the ELR) with an intermittent stalling problem that two other shops couldn’t solve. There were no consistent trouble codes, just a random loss of power. After checking all the basics—fuel pressure, wiring, sensors—we focused on the ECM. On the surface, it seemed fine. However, by monitoring live data streams during a long test drive, we saw momentary communication dropouts from the module right before a stall. It was a classic case of internal ECM failure under thermal load. We installed a VIN-programmed module just like this one, and the problem was solved instantly. The customer saved hundreds, if not thousands, in further diagnostic fees.
Is Your Vehicle Showing These Telltale Signs of ECM Failure?
- ✔ Engine cranks but refuses to start.
- ✔ Unexplained stalling or rough idling.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Check Engine Light is on with codes like P0601, P0606, or U0100 (Communication Loss).
- ✔ Other warning lights (ABS, Traction Control) illuminate without a clear cause.
- ✔ The cooling fans run constantly, even when the engine is cold.
A Straightforward Guide to Installation
Replacing your 2014-2016 ELR Engine Control Module is a manageable job for a DIY enthusiast. Because we handle the programming, you won’t need any special electronic tools.
- Safety First: Disconnect the negative terminal from your vehicle’s 12V battery and secure it away from the post.
- Locate the ECM: On the 2014-2016 Cadillac ELR, the ECM is found in the left-hand (driver’s side) rear of the engine compartment. For other models, its location may vary (e.g., front of the engine bay on Silverado/Sierra trucks).
- Disconnect Connectors: Carefully release the locking tabs on the wiring harness connectors and pull them straight out from the module. Do not force them.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket. Keep the mounting hardware as you will reuse it.
- Install the New Module: Mount your new, pre-programmed ECM onto the bracket and secure it with the original hardware.
- Reconnect Everything: Firmly plug the wiring harnesses back into the new module until they click into place. Reconnect the negative battery terminal.
- Final Check: Your vehicle may require a security relearn procedure, which can often be completed by cycling the key. In most cases, the vehicle will start and run correctly immediately.
Verified Vehicle Compatibility
This module is a direct-fit replacement for a wide range of GM vehicles and interchanges with part numbers 12668866, 12668994, 12643636, and others. Please verify your vehicle is on this list. We program the module based on the VIN you provide to ensure perfect compatibility.
- Cadillac ELR: 2014-2016 (Gasoline)
- Chevrolet Cruze: 2012-2016 (See specific options in full list)
- Chevrolet Sonic: 2012-2016 (See specific options in full list)
- Chevrolet Silverado 2500/3500: 2012-2016 (6.0L)
- GMC Sierra 2500/3500: 2012-2016 (6.0L)
- Chevrolet Express / GMC Savana Vans: 2016 (4.8L, 6.0L)
- Buick Encore: 2013-2016 (1.4L)
- …and many more. See the detailed compatibility chart.
Frequently Asked Questions
Frequently Asked Questions
What is VIN programming?
VIN programming is the process of loading your vehicle’s specific software and settings into the Engine Control Module. This includes information about your engine, transmission, and factory-installed options. We perform this service before shipping, so the part is ready to install when you receive it.
Do I need to do anything else after I install this ECM?
In most cases, no. The module is plug-and-play. Some vehicles may require a simple key-cycle or throttle-body relearn procedure that does not require special tools. Instructions can typically be found online or in a service manual.
How do I provide my VIN number?
After you complete your purchase, you will need to send us your 17-digit Vehicle Identification Number (VIN). We cannot ship the module until we receive this information to ensure correct programming.
Will this fix my Check Engine Light?
If the Check Engine Light is on due to an internal failure of the original ECM (e.g., code P0601), this part will resolve the issue. However, if the light is on for another reason, such as a faulty sensor, that issue will still need to be addressed separately.
Is this a new or used part?
This is a high-quality, tested, and verified used component that has been expertly programmed with the latest software for your vehicle, offering a reliable and cost-effective solution.