Is Your Cadillac XTS Running Rough or Showing a Check Engine Light?
As a technician with over two decades of experience under the hood, I know the frustration that comes with a vehicle that just won’t cooperate. You might be dealing with a persistent check engine light, unexplained stalling, poor fuel economy, or even a no-start condition. These are classic signs that the brain of your engine management system—the Engine Control Module (ECM)—is failing. When the ECM has an internal fault, it can send you chasing phantom sensor codes for weeks. This isn’t just a part; it’s the central command for your vehicle’s performance and reliability.
The Direct Solution: A VIN-Programmed 2017-2019 XTS ECM
Forget the expensive dealership visits and the uncertainty of a used module. We offer a dependable, straightforward solution. This Engine Control Module is meticulously programmed to your vehicle’s specific Vehicle Identification Number (VIN) before it ever leaves our facility. We load it with the latest, most stable software updates directly from GM, ensuring it communicates flawlessly with your XTS and all its related systems. This isn’t a generic, one-size-fits-all part; it’s prepared specifically for your car.
A Real-World Diagnostic Story
“A customer’s 2018 Impala came in last month with a persistent P0304 (Cylinder 4 Misfire) code. The owner had already replaced the spark plug, ignition coil, and fuel injector on that cylinder, but the misfire and rough idle wouldn’t go away. After confirming the new parts were good, my diagnostic process led me to the ECM. Using a scope, I found the driver circuit for the #4 ignition coil inside the ECM was weak and failing under load. We installed one of our VIN-programmed ECMs, and the car ran perfectly. It’s a classic case where the problem isn’t the component being monitored, but the monitor itself—the ECM.”
Common Symptoms of a Failing GM ECM:
- ✔ Persistent Check Engine Light (CEL) that won’t clear
- ✔ Engine stalling, stumbling, or hesitating during acceleration
- ✔ Noticeable decrease in fuel efficiency
- ✔ Vehicle enters a reduced power or “limp” mode
- ✔ No communication with a diagnostic scan tool
- ✔ Intermittent or complete no-start condition
- ✔ False error codes for sensors that have already been replaced
Plug-and-Play Installation: No Dealer Visit Required
Our VIN programming service makes installation a simple swap. Because the security information and vehicle-specific parameters are already loaded, you can avoid the costly programming and key relearn procedures required by the dealer. For the 2017-2019 Cadillac XTS with the 3.6L LFX engine, the ECM is typically located in the engine compartment. Follow these general steps for a successful installation:
- Safety First: Disconnect the negative terminal from your vehicle’s battery and wait 10-15 minutes for the system capacitors to discharge.
- Locate the ECM: On the XTS and many similar GM models (like the Impala, Regal, Equinox, and Terrain), you’ll find the ECM in the left-hand (driver’s side) of the engine compartment.
- Disconnect Connectors: Carefully release the locking tabs and disconnect the wiring harnesses from the old ECM. Inspect the pins and connectors for any corrosion or damage and clean them with a dedicated electronics cleaner if necessary.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket.
- Install the New Module: Mount your new, pre-programmed ECM securely onto the bracket and reconnect the wiring harnesses. Ensure they click firmly into place.
- Reconnect Battery: Reattach the negative battery terminal. The vehicle is now ready to start.
Guaranteed Fitment for Your Vehicle
This module, part number 12666070, is a direct replacement for service numbers 12667002 and 12667189. It is confirmed to fit the following vehicles with the specified options:
- Cadillac XTS: 2017-2019 (3.6L, VIN 3 – 8th digit, opt LFX)
- Chevrolet Caprice: 2017 (3.6L)
- Chevrolet Traverse: 2017 (Behind fan shroud)
- Chevrolet Impala: 2017-2019
- Chevrolet Equinox: 2017 (LH engine compartment)
- GMC Acadia: 2017 (Limited, VIN J – 11th digit, behind fan shroud)
- GMC Terrain: 2017 (LH engine compartment)
- Buick Enclave: 2017 (Behind fan shroud)
- Buick Regal: 2017 (LH engine compartment)
- Buick Verano: 2017
After purchase, simply provide us with your vehicle’s VIN. We’ll handle the programming, ensuring you receive a part that restores your vehicle’s performance and reliability right out of the box.