Restore Peak Performance to Your GM Truck or SUV
Is your 2018 Sierra Denali 1500 suffering from baffling electrical problems? Intermittent stalling, a persistent check engine light, or a complete no-start condition can often be traced back to a failing Engine Control Module (ECM). As the central computer for your engine, its health is critical. This replacement ECM, part number 12704475, is the definitive solution to get your vehicle running reliably again. We take the guesswork out of the repair by programming the module specifically to your vehicle’s VIN with the latest GM-certified software before it ever leaves our facility. This ensures proper communication and function right out of the box, saving you a costly trip to the dealership.
A Technician’s Notebook: The No-Communication Nightmare
I once had a 2018 Silverado in my bay with a classic case of ECM failure. The owner had already replaced the battery and alternator, but the truck would crank but not start, and the dash was lit up like a Christmas tree. My scan tool couldn’t communicate with the engine computer—a dead giveaway. The dreaded U0100 (Lost Communication with ECM/PCM) code was stored in other modules. After verifying power and ground to the ECM connector, we confirmed the module itself was the culprit. Installing a pre-programmed unit like this one restored communication instantly. After a quick security relearn, the truck fired right up, and all the warning lights were gone. This is a common failure, and having a VIN-matched module is the key to an efficient repair.
Is Your Vehicle Showing These Signs of ECM Failure?
- ✔ No-start or crank-no-start conditions.
- ✔ Engine stalling or hesitating for no apparent reason.
- ✔ A persistent Check Engine Light that won’t clear.
- ✔ Diagnostic Trouble Codes (DTCs) related to internal module failure, such as P0601, P0606, or P062F.
- ✔ Loss of communication with the ECM (DTC U0100).
- ✔ Poor fuel economy and decreased engine performance.
- ✔ Inconsistent or erratic automatic transmission shifting.
A Straightforward Guide to Installation
Replacing the ECM is a manageable job for a confident DIYer or any professional technician. Our VIN programming service handles the most complex part for you. Follow these general steps for a successful installation:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before beginning any electrical work.
- Locate the ECM: On most compatible trucks and SUVs like the Sierra or Silverado, the ECM is located in the engine compartment on the driver’s side, near the firewall or inner fender.
- Disconnect and Remove: Carefully unplug the electrical connectors. They have locking tabs that must be released. Then, unbolt the old ECM from its mounting bracket.
- Install the New Module: Mount the new ECM in the same location and securely reconnect all electrical harnesses. Ensure they click into place.
- Reconnect Battery: Reattach the negative battery terminal.
- Perform Relearn Procedures: This is a critical step. You will likely need to perform a Vehicle Theft Deterrent System (VTDS) relearn using a compatible scan tool with access to GM’s TIS2WEB or Techline Connect service. The vehicle may not start until this is completed. Other procedures like a Crankshaft Position Variation relearn may also be required.
Guaranteed Fitment for Your GM Vehicle
This module is a direct-fit replacement for a wide range of GM vehicles. Please verify your original part number or consult the list below. This ECM is compatible with part numbers 12704475, 12692069, 12680656, 12686383, and 12688528.
- Cadillac Escalade / ESV: 2018
- Cadillac XTS: 2018 (3.6L, VIN 8)
- Chevrolet Corvette: 2018, 2019 (LT1 & LT4)
- Chevrolet Express 2500 / 3500 Van: 2018 (4.3L)
- Chevrolet Silverado 1500: 2018
- Chevrolet Suburban 1500: 2018
- Chevrolet Tahoe: 2018
- GMC Savana 2500 / 3500 Van: 2018 (4.3L)
- GMC Sierra 1500 / Denali 1500: 2018
- GMC Yukon / Yukon XL 1500: 2018
Frequently Asked Questions
Why do you need my VIN?
Your Vehicle Identification Number (VIN) is essential. We use it to load your vehicle’s exact factory software and calibrations onto the ECM. This ensures the module works correctly with your engine, transmission, and other systems, preventing compatibility issues.
What is a security relearn and is it difficult?
The security relearn (or Vehicle Theft Deterrent System relearn) syncs the new ECM with your vehicle’s anti-theft system. Without it, the system may prevent the engine from starting. This procedure requires a professional scan tool with access to GM’s online service (TIS2WEB/Techline Connect). It is the buyer’s responsibility to have this procedure performed by a qualified shop if needed.
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 this replacement module will 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 repaired.
Is this a plug-and-play part?
It is as close as you can get. We handle the programming, which is the most complex part. However, due to modern vehicle security systems, the final security relearn must be performed on the vehicle after installation. Other relearns for specific components may also be necessary.
How do I find my original part number?
The part number is printed on a sticker on the case of your current ECM. You may need to remove the module to see it clearly. Verifying this number is the best way to ensure you are ordering the correct part.