Restore Peak Performance to Your GM Vehicle
As a technician with over two decades of experience under the hood, I’ve seen firsthand the frustration that a failing Engine Control Module (ECM) can cause. Your 2017 GMC Terrain might be experiencing perplexing issues like random stalling, a persistent Check Engine Light, poor fuel economy, or a complete no-start condition. These aren’t just annoyances; they’re signs that the very brain of your engine is struggling. This replacement ECM, part number 12667002, is the definitive solution to get your vehicle running reliably again.
What sets this module apart is our commitment to a seamless repair. Before this ECM ever leaves our facility, we flash it with the latest official GM software updates, precisely programmed to your vehicle’s unique Vehicle Identification Number (VIN). This critical step eliminates the need for an expensive trip to the dealership for programming. You receive a component that is truly ready for installation, designed to restore the original performance and efficiency of your engine. When you’re dealing with complex electronics, having a part that’s guaranteed to communicate correctly from the moment you plug it in is more than a convenience—it’s peace of mind.
Common Signs of a Failing Engine Computer
- ✔ The Check Engine Light is on and won’t go away, often with communication-related or internal processor fault codes (e.g., P0601, P0606).
- ✔ Your engine cranks but refuses to start, or starts and immediately stalls.
- ✔ Unexplained drops in fuel efficiency and noticeable loss of power.
- ✔ The engine runs rough, misfires, or hesitates during acceleration.
- ✔ Automatic transmission shifts erratically or harshly.
- ✔ Intermittent issues that disappear and then return without a clear cause.
From the Diagnostic Bay: A Tricky Intermittent Stall
I remember a 2017 Equinox—which shares its platform with the Terrain—that came into my shop with a maddening problem. The owner said it would stall without warning, usually after 20-30 minutes of driving, and then refuse to restart for an hour. There were no consistent trouble codes stored, making diagnosis a nightmare. After verifying fuel pressure and spark were good when it was running, we focused on the ECM. By monitoring live data, we noticed that key sensor readings would flatline just before a stall. It was a classic case of internal ECM failure due to heat soak. We installed a VIN-programmed ECM just like this one, and the problem was solved permanently. That’s the difference a quality, correctly prepared component makes.
A Straightforward Guide to Installation
Replacing your 2017 Terrain ECM is a manageable job for a confident DIYer. Follow these steps carefully for a successful installation.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 15 minutes to allow the system’s capacitors to discharge.
- Locate the ECM: On the 2017 Terrain and Equinox, the ECM is typically found in the engine compartment on the driver’s side, often near the fuse box or firewall.
- Disconnect Connectors: Carefully release the locking tabs on the electrical wiring harnesses and gently pull them straight out from the module. Never force them. Inspect the connectors for any corrosion or damage.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket. Keep the hardware safe as you will need it for the new module.
- Install the New ECM: Mount the new, pre-programmed ECM onto the bracket and secure it with the original hardware.
- Reconnect and Secure: Firmly plug the wiring harnesses back into the new ECM until they click into place. Ensure the locking tabs are fully engaged.
- Final Steps: Reconnect the negative battery terminal. It is often necessary to perform a security relearn procedure, which can typically be done without special tools. Instructions can be found online or in your vehicle’s service manual.
Verified Vehicle Compatibility
This module is a direct-fit replacement for several GM models and interchanges with part numbers 12666070 and 12667189. Please confirm your vehicle is on this list:
- ✔ 2017 Cadillac XTS: (3.6L, VIN 3)
- ✔ 2017-2019 Cadillac XTS: (3.6L, VIN 3, LFX)
- ✔ 2017-2019 Chevrolet Impala
- ✔ 2017 Chevrolet Caprice: (3.6L)
- ✔ 2017 Chevrolet Traverse: (Behind fan shroud)
- ✔ 2017 Chevrolet Equinox: (LH engine compartment)
- ✔ 2017 GMC Acadia: (VIN J, Limited, behind fan shroud)
- ✔ 2017 GMC Terrain: (LH engine compartment)
- ✔ 2017 Buick Enclave: (Behind fan shroud)
- ✔ 2017 Buick Regal: (LH engine compartment)
- ✔ 2017 Buick Verano
Your Solution is Here
Don’t let a faulty computer keep you off the road. This pre-programmed 2017 Terrain ECM is the most reliable and efficient way to resolve complex engine management problems. By providing us with your VIN at checkout, you ensure a perfect software match for a smooth, hassle-free repair.
Frequently Asked Questions
Do I need to do any programming myself?
No. We handle all the programming before shipment. We flash the module with the latest GM software using the VIN you provide, so it’s ready for installation right out of the box.
What information do you need from me?
After you place your order, you must provide us with your vehicle’s 17-digit Vehicle Identification Number (VIN). This is essential for us to program the ECM correctly for your specific vehicle.
Is a security relearn required after installation?
In most cases, yes. GM vehicles have an anti-theft system that will need to be synchronized with the new ECM. This is often called a ‘Passlock’ or ‘Passkey’ relearn procedure and can usually be completed in about 30 minutes without any special tools.
Will this fix my specific problem?
This ECM is a direct replacement for a faulty original unit and will resolve issues caused by ECM failure. However, it’s crucial to ensure your vehicle has been properly diagnosed. This part will not fix problems related to other failed sensors or wiring issues.
Does this part fit other part numbers?
Yes, this ECM is a direct replacement for part numbers 12667002, 12666070, and 12667189.