Is Your GM Vehicle Acting Up? Get a Reliable, Programmed Engine Control Module
As a technician with over two decades of experience under the hood, I’ve seen firsthand how a failing Engine Control Module (ECM) can bring even the most powerful vehicles to a dead stop. If your 2018-2019 Corvette, Silverado, or other compatible GM vehicle is suffering from frustrating issues like intermittent stalling, a no-start condition, poor fuel economy, or a persistent Check Engine Light, the problem often points directly to the vehicle’s computer. This isn’t just a part; it’s the central command center for your engine’s performance and efficiency.
This listing is for a direct-replacement ECM, part number 12704475 (which also replaces 12692069, 12680656, 12686383, and 12688528). We take the guesswork and high dealership costs out of the equation. Before we ship it, we program the module with the latest official GM software calibrated specifically to your vehicle’s VIN. This ensures that when you receive it, it’s ready for the final installation and relearn steps, restoring your vehicle’s original performance and reliability.
A Technician’s Notebook: The Ghost in the Machine
I remember a 2018 Sierra 1500 that came into the shop on a tow truck. The owner was frustrated; it would crank but never start, and two other shops had already replaced the fuel pump and crank sensor with no luck. The scanner showed a U0100 code—Lost Communication with ECM. After verifying power and ground at the ECM connector, it was clear the module itself was dead. We installed a VIN-programmed unit just like this one, performed the quick security relearn, and the truck fired up on the first try. The customer saved hundreds compared to the dealer quote and was back on the road the same day. This is a common failure, and having a pre-programmed module is the fastest path to a solid repair.
Common Signs of a Failing ECM
A faulty engine computer can cause a wide range of symptoms. If you’re experiencing any of the following, a replacement 2018-2019 Corvette ECM could be the solution you need. Look out for:
- âś” Check Engine Light is illuminated with communication-related Diagnostic Trouble Codes (DTCs) like P0601, P0606, or U0100.
- âś” The engine cranks but refuses to start.
- âś” Intermittent stalling or rough idling for no apparent reason.
- âś” A noticeable drop in fuel efficiency.
- ✔ The vehicle is in “limp mode,” with reduced power.
- âś” Unexplained transmission shifting problems.
A Straightforward Guide to Installation
Replacing the ECM is a manageable task for an experienced DIYer or any professional technician. Our pre-programming service handles the most complex part, leaving you with the physical installation and final setup.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the ECM: The location varies by model. On a Corvette, it’s typically in the RH cowl area under the dash. On a Silverado/Sierra, it’s in the LH front of the engine compartment. Consult a service manual for your specific vehicle.
- Disconnect and Remove: Carefully unplug the wiring harness connectors. Be gentle with the locking tabs. Then, unbolt the old ECM from its mounting bracket and remove it.
- Install the New ECM: Mount the new module in place and securely fasten it. Reconnect the wiring harnesses, ensuring each plug clicks firmly into place.
- Reconnect the Battery: Re-attach the negative battery terminal.
- Perform Final Relearns: This is a critical step. If the vehicle does not start, you must perform the Vehicle Theft Deterrent (VTD) relearn using a GM-compatible scan tool with access to Tis2web or Techline Connect. Other procedures like a crankshaft variation relearn may also be necessary. This is the responsibility of the installer.
Will This Fit My Vehicle?
We guarantee this module is compatible with the following vehicles. Please match your part number or vehicle to this list to ensure proper fitment. This module, part number 12704475, is the correct service replacement for several original part numbers.
- 2018-2019 Corvette: (RH cowl under dash), fits LT1 & LT4 engines.
- 2018 Cadillac Escalade / Escalade ESV: (Engine compartment).
- 2018 Cadillac XTS: (3.6L, VIN 8 – opt LF3).
- 2018 Chevrolet Silverado 1500 / GMC Sierra 1500: (LH front engine compartment), verify ID 12680656.
- 2018 GMC Sierra Denali 1500: (LH front engine compartment), verify ID 12686383.
- 2018 Chevrolet Suburban 1500 / Tahoe: (LH front engine compartment).
- 2018 GMC Yukon / Yukon XL 1500: (LH front engine compartment).
- 2018 Chevrolet Express 2500/3500 & GMC Savana 2500/3500 Vans: (LH rear engine compartment), 4.3L engine.
Do I need to do anything after I install this ECM?
Do I need to do anything after I install this ECM?
Yes. While we program the module to your VIN, you or your mechanic must perform the Vehicle Theft Deterrent (VTD) relearn procedure upon installation. This syncs the new ECM to your vehicle’s anti-theft system. Other relearns, like for the crankshaft position sensor, may also be required depending on your vehicle.
What information do you need from me?
After you complete your purchase, you must provide us with your vehicle’s 17-digit Vehicle Identification Number (VIN). We cannot program and ship your ECM without it. This ensures we load the correct GM-certified software for your specific vehicle configuration.
What if I install it and my car doesn’t start?
A no-start condition after installation is almost always caused by the need for the VTD relearn. The anti-theft system is preventing the engine from running until the new ECM is properly introduced. This is a standard security feature on all modern GM vehicles and requires a capable scan tool to complete.
Is this a used part?
This is a quality, tested OEM part that has been inspected and prepared for service. It is programmed with the newest software available from GM for your vehicle, ensuring it functions correctly and resolves common electronic issues.
Will this fix my specific problem?
This part is a direct solution for a failed ECM. It is essential to have your vehicle properly diagnosed before ordering. This module will correct issues directly caused by a faulty computer, such as internal processor faults (P0606) or communication loss (U0100), but it will not fix problems with other sensors or wiring on the vehicle.