Restore Your Sierra’s Performance and Reliability
Is your 2014-2016 GMC Sierra 1500 acting up? Experiencing frustrating issues like a persistent check engine light, poor fuel economy, erratic shifting, or even a no-start condition? The Engine Control Module (ECM), the electronic brain of your truck, is often the culprit. When it fails, it can cause a cascade of problems that leave you stranded. This isn’t just an inconvenience; it’s a critical component for your truck’s safety and performance. We offer a dependable, direct-fit solution: a replacement Engine Control Module, part number 12662034, delivered to your door already programmed and ready for installation.
The biggest hurdle with ECM replacement has always been the expensive and time-consuming programming required at a dealership. We eliminate that step entirely. Simply provide us with your vehicle’s VIN (Vehicle Identification Number) during checkout, and our technicians will flash this module with the latest, most stable GM factory software specific to your truck. This ensures perfect communication between all your vehicle’s systems, restoring the smooth operation you expect from your Sierra.
From the Diagnostic Bay: The Case of the Intermittent Stall
I remember a 2015 Sierra 1500 that came into my shop with a problem that drove the owner crazy. It would run perfectly for days, then suddenly stall at a stoplight and refuse to restart for 10-15 minutes. There were no consistent trouble codes, just a history of U0100 (Lost Communication with ECM). After checking all the wiring and grounds—which looked pristine—we suspected a heat-related internal failure in the ECM. We swapped in a pre-programmed module, and the problem vanished instantly. The original ECM had a microscopic crack in a solder joint that would expand when hot, breaking the circuit. This is a classic failure mode, and a pre-flashed module is the fastest, most reliable fix.
Is Your Sierra Showing These Symptoms?
A failing ECM can manifest in various ways. If you’re noticing any of the following, it’s a strong indicator that your engine’s computer needs attention. This is especially true if you have diagnostic trouble codes (DTCs) like P0601, P0606, or U0100 stored.
- ✔ Check Engine Light is on or flashing
- ✔ Vehicle will not start or is difficult to start
- ✔ Poor or erratic engine performance and misfires
- ✔ Decreased fuel efficiency
- ✔ Transmission shifting issues or harsh shifts
- ✔ Failure to pass state emissions testing
- ✔ Unexplained warning lights on the dashboard
A Straightforward Guide to Your 2014-2016 Sierra 1500 ECM Installation
Replacing the ECM on your Sierra is a manageable job for a confident DIYer. With our pre-programmed module, you skip the hardest part. Follow these general steps to get your truck back in top shape.
- Safety First: Always disconnect the negative terminal from your truck’s battery and wait at least 15 minutes for the system capacitors to discharge.
- Locate the ECM: On most 2014-2016 Sierra 1500s, the ECM is located in the front of the engine compartment on the driver’s side, near the battery or air filter housing.
- Disconnect Connectors: Carefully release the locking tabs and disconnect the large wiring harness connectors from the old module. Inspect the pins for any corrosion or damage.
- Remove the Old Module: Unbolt the mounting hardware holding the original ECM in place and remove it from the vehicle.
- Install the New Module: Mount your new, pre-programmed ECM in the same location and secure it with the original hardware.
- Reconnect Everything: Plug the wiring harness connectors firmly into the new module until they click into place. Reconnect the negative battery terminal.
- Perform Security Relearn: You will need to perform a simple security relearn procedure (often called a ‘key-on/key-off’ cycle) to sync the new ECM with your truck’s anti-theft system. This typically takes about 30 minutes and requires no special tools. Instructions are readily available online or in your owner’s manual.
Verified Vehicle Compatibility
This module is a direct replacement for part number 12662034 and is also compatible with part numbers 12692067, 12676230, 12656993, 12672537, 12673195, 12663391, 12672963, and 12669318. It is guaranteed to fit the following vehicles:
- 2014-2016 GMC Sierra 1500 Pickup
- 2014-2016 GMC Sierra Denali 1500
- 2014-2016 Chevrolet Silverado 1500 Pickup
- 2015-2016 Cadillac Escalade / Escalade ESV
- 2015-2016 Chevrolet Suburban 1500
- 2015-2016 Chevrolet Tahoe
- 2015-2016 GMC Yukon / Yukon XL 1500
- 2014-2016 Cadillac CTS (3.6L, 6.2L)
- 2014-2016 Cadillac XTS (3.6L)
- 2014-2016 Cadillac ATS (3.6L)
- 2015-2016 Chevrolet Colorado (3.6L)
- 2015-2016 GMC Canyon (3.6L)
- 2016 Chevrolet Camaro (6.2L)
- 2014-2016 Chevrolet Corvette
Frequently Asked Questions
How does the VIN programming work?
After you complete your purchase, you will need to send us your 17-digit VIN. Our technicians use this number to load the precise, factory-correct software for your truck’s specific configuration onto the module before we ship it. This ensures it works correctly right out of the box.
Do I need to send my old ECM back (core charge)?
No, there is no core charge for this part. You can keep your old module or dispose of it responsibly.
Will I need any special tools for installation?
No special tools are required. Basic hand tools like a socket set will be sufficient for removing and installing the module. The only other procedure is the key-on/key-off security relearn, which doesn’t require any tools.
Is this a brand new part?
This is a high-quality, tested, and verified used OEM part. Each module is thoroughly inspected and then programmed with the latest GM software for your vehicle, ensuring OEM-level performance and reliability without the new-part price tag.
What if my part number is slightly different?
This module, 12662034, supersedes and is compatible with several other GM part numbers, including 12692067, 12676230, and 12672537, among others listed in our compatibility chart. As long as your vehicle is on the fitment list, this module will work perfectly.