Restore Peak Performance to Your GM Truck or SUV
Is your 2018 GMC Sierra 1500 or other compatible GM vehicle suffering from frustrating, hard-to-diagnose issues? As a technician with over two decades of experience under the hood, I’ve seen firsthand how a failing Engine Control Module (ECM) can wreak havoc. From erratic idling and poor fuel economy to a dreaded no-start condition, the ECM is the brain of your engine, and when it falters, the symptoms can be maddening. This isn’t just a part; it’s the central command for your vehicle’s performance and reliability.
We take the guesswork and dealership hassle out of the equation. This genuine GM ECM, compatible with part number 12680656, arrives at your door pre-programmed with the latest factory software specifically for your vehicle. Simply provide your Vehicle Identification Number (VIN) at checkout, and our experts will handle the complex programming. This ensures that when you install your new 2018 Sierra 1500 ECM, it communicates seamlessly with your truck’s existing systems.
A Technician’s Notebook: The Intermittent Gremlin
I remember a 2018 Silverado that came into the bay with a complaint that stumped two other shops. The owner described random stalling at stoplights and an occasional hard start, but with no consistent Check Engine Light. We checked fuel pressure, ignition components, and sensors—all tested fine. It wasn’t until we monitored live data during a long test drive that we saw the ECM’s processor voltage drop intermittently, just for a split second. That was the culprit. A failing internal component was causing these ghost-like issues. Replacing the ECM with a properly programmed unit solved the problem instantly, saving the customer from endless parts-swapping.
Is Your Vehicle Showing These Symptoms?
A faulty ECM can manifest in numerous ways. If you’re experiencing any of the following, your engine’s computer may be the root cause. This is especially true if you’ve scanned for codes and found internal processor errors.
- ✔ Unexplained Check Engine Light (CEL) illumination
- ✔ Diagnostic Trouble Codes (DTCs) such as P0601 (Internal Control Module Memory Check Sum Error) or P0606 (ECM/PCM Processor Fault)
- ✔ Vehicle will not start or is very difficult to start
- ✔ Poor or erratic engine performance and hesitation
- ✔ Decreased fuel efficiency
- ✔ Stalling or rough idling
- ✔ Transmission shifting problems or communication errors with the TCM
A Straightforward Guide to Installation
Replacing your 2018 Sierra 1500 ECM is a manageable job for a confident DIYer or any professional mechanic. With our pre-programming service, the most difficult step is already done for you.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the ECM: On the Sierra/Silverado, the ECM is typically found in the engine compartment on the driver’s side, near the front. Consult a service manual for your specific vehicle if you’re unsure.
- Disconnect and Remove: Carefully unplug the electrical connectors. There are usually locking tabs that need to be released. Once disconnected, unbolt the old ECM from its mounting bracket.
- Install the New ECM: Mount the new module securely onto the bracket and reconnect the electrical connectors, ensuring they click firmly into place.
- Reconnect Battery: Re-attach the negative battery terminal.
- Perform Relearn Procedures: Turn the key to the ‘ON’ position. IMPORTANT: If the vehicle does not start, a Vehicle Theft Deterrent System (VTDS) relearn is required. This must be done using a professional scan tool with access to GM’s TIS2Web or Techline Connect service. This is the responsibility of the installer. Other procedures like a crankshaft position variation relearn may also be necessary for optimal performance.
Guaranteed Fitment for Your GM Vehicle
This module is a direct replacement for several part numbers and fits a wide range of popular GM models. Please verify your vehicle and original part ID to ensure compatibility.
- ✔ Chevrolet Corvette: 2018-2019 (LT1 & LT4)
- ✔ Chevrolet Silverado 1500 Pickup: 2018 (ID 12680656)
- ✔ GMC Sierra 1500 Pickup: 2018 (ID 12680656)
- ✔ GMC Sierra Denali 1500: 2018 (ID 12686383)
- ✔ Cadillac Escalade / ESV: 2018
- ✔ Chevrolet Tahoe / Suburban 1500: 2018
- ✔ GMC Yukon / Yukon XL 1500: 2018
- ✔ Chevrolet Express 2500/3500 Van: 2018 (4.3L)
- ✔ GMC Savana 2500/3500 Van: 2018 (4.3L)
- ✔ Cadillac XTS: 2018 (3.6L, opt LF3)
This part replaces the following part numbers: 12704475, 12692069, 12680656, 12686383, 12688528.
Frequently Asked Questions
Frequently Asked Questions
2018 Sierra 1500 ECM
Will this fix my check engine light?
If your check engine light is caused by an internal failure of the old ECM (like codes P0601-P0606), then this new will resolve the issue. If the light is on due to a faulty sensor or other component, that separate issue will still need to be addressed.