If you’re dealing with frustrating engine problems in your 2017 GMC Terrain—like stalling, no-start conditions, or a persistent Check Engine Light—a failing Engine Control Module (ECM) is often the culprit. As a technician with over two decades of experience, I’ve seen firsthand how a faulty ECM can disrupt everything from fuel economy to engine timing. This isn’t just a part; it’s the brain of your vehicle’s engine, and when it fails, it can cause a cascade of confusing issues. This replacement ECM is your reliable, straightforward solution to restore your vehicle’s performance and peace of mind.
We take the guesswork and high costs out of the equation. Unlike a standard replacement that requires an expensive trip to the dealership for programming, this module arrives at your door ready to install. Simply provide your vehicle’s VIN during checkout, and our experts will program the unit with the latest GM software updates specific to your vehicle. This ensures seamless communication between the module and your vehicle’s other systems, just as the factory intended.
Common Signs of a Failing Engine Control Module
- ✔️ The vehicle cranks but refuses to start.
- ✔️ Intermittent stalling or rough idling, especially when warm.
- ✔️ A noticeable drop in fuel efficiency.
- ✔️ The Check Engine Light is illuminated with codes like P0601 (Internal Control Module Memory Check Sum Error) or P0606 (ECM/PCM Processor Fault).
- ✔️ Poor acceleration or hesitation during gear shifts.
- ✔️ Inconsistent or erratic behavior from electronic components tied to the engine.
From the Diagnostic Bay: The Misleading Fault
A few months back, a 2017 Chevy Equinox (which shares its platform and ECM with the Terrain) was towed into my shop. The owner was convinced the transmission was failing. It was shifting harshly and sometimes seemed to get ‘stuck’ in gear. The codes were all over the place, some pointing to the transmission, others to sensor circuits. After chasing down several dead ends, we hooked up our most advanced diagnostic scanner to monitor live data from the ECM. We found that the ECM’s processor was intermittently dropping communication packets. It wasn’t the transmission at all; the faulty 2017 Terrain ECM was sending corrupt signals, confusing the transmission control module. We installed a VIN-programmed ECM, and all the issues vanished instantly. It’s a classic case of the symptoms not always pointing to the source.
A Straightforward Guide to Installation
Installing your pre-programmed 2017 Terrain ECM is a manageable job for a confident DIYer. Following these steps will help ensure a smooth process.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 15 minutes to allow all systems to discharge.
- Locate the ECM: On the 2017 GMC Terrain and Chevy Equinox, the ECM is typically found in the engine compartment on the driver’s side (LH), often near the fuse box or air filter housing.
- Disconnect the Connectors: Carefully release the locking tabs on the electrical connectors and pull them straight out. Never force them, as this can damage the pins. Inspect the connectors for any corrosion or damage.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket. Keep the hardware, as you will need it to install the new unit.
- Install the New ECM: Mount your new, pre-programmed ECM onto the bracket and secure it with the original hardware.
- Reconnect Everything: Firmly plug the electrical connectors into the new module until they click into place. Reconnect the negative battery terminal.
- Final Step: In some cases, a security or anti-theft relearn procedure may be necessary. This can often be done without special tools by cycling the key. Consult your vehicle’s service information for specific steps if required.
Verified Vehicle Compatibility
This ECM is a direct replacement for part numbers 12667002, 12666070, and 12667189. It is guaranteed to fit the following vehicles and options:
- ✔️ 2017 Cadillac XTS: With 3.6L engine (VIN 3, 8th digit, opt LFX)
- ✔️ 2017-2019 Chevrolet Impala
- ✔️ 2017 Chevrolet Caprice: With 3.6L engine
- ✔️ 2017 Chevrolet Traverse: Located behind the fan shroud
- ✔️ 2017 Chevrolet Equinox: Located in the LH engine compartment
- ✔️ 2017 GMC Terrain: Located in the LH engine compartment
- ✔️ 2017 GMC Acadia: Limited models (VIN J, 11th digit), located behind the fan shroud
- ✔️ 2017 Buick Enclave: Located behind the fan shroud
- ✔️ 2017 Buick Regal: Located in the LH engine compartment
- ✔️ 2017 Buick Verano
Frequently Asked Questions
Why do you need my VIN?
Your Vehicle Identification Number (VIN) is essential for us to program the ECM with the correct software and calibrations for your specific vehicle. This ensures proper engine function, emissions compliance, and communication with other onboard modules, making the installation process as simple as possible.
Is this a simple plug-and-play installation?
Yes, for most vehicles. Because we pre-program the module to your VIN, it eliminates the need for dealer-level programming tools. In some cases, a simple key-cycle ‘anti-theft relearn’ procedure may be required after installation, which you can typically do yourself.
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 replacing it with this programmed unit should resolve the issue. However, if the light is on due to a faulty sensor or other component, that separate issue will still need to be addressed.
Where is the ECM located on my 2017 GMC Terrain?
On the 2017 Terrain, the Engine Control Module is located in the engine bay, on the left-hand (driver’s) side. It’s typically mounted near the underhood fuse block.
Do I need to send my old ECM back?
This listing does not require a core return. You can keep your old module, though we always recommend recycling old electronics responsibly.