Is Your Silverado 3500 Running Rough? The Engine’s Brain Might Be the Problem.
As a technician with over two decades in the bay, I’ve seen it all. A powerful workhorse like your 2012-2016 Silverado 3500 suddenly starts acting upโstalling at intersections, poor fuel economy, a persistent Check Engine Light, or even refusing to start. These aren’t just annoyances; they’re problems that cost you time and money. Often, the culprit is the very component that controls everything: the Engine Control Module (ECM).
The ECM is the central computer for your truck’s engine. It processes information from dozens of sensors to manage fuel injection, ignition timing, and transmission shifts. When it fails, the symptoms can be unpredictable and frustrating. This isn’t a part you can ignore. This is the solution to get your truck back to its reliable, powerful self.
The Direct Solution: A VIN-Programmed 2012-2016 Silverado 3500 ECM
Forget expensive dealership visits and the hassle of finding a shop that can program a new module. We handle the critical step for you. This genuine GM Engine Control Module, part number 12670335, arrives at your door programmed with the latest GM software specifically for your truck’s Vehicle Identification Number (VIN). It’s a true plug-and-play solution that restores factory performance and communication.
Expert Pro Tip: Check Your Grounds Before You Swap!
Before you condemn your old ECM, do a quick but crucial check. On these GM trucks, the main engine-to-chassis ground strap is notorious for corroding. I’ve seen dozens of trucks come into my shop with bizarre electrical issues that looked like a bad ECM, but it was just a faulty ground connection. A poor ground can cause voltage fluctuations that not only mimic ECM failure but can also damage the new module you’re about to install. Locate the strap (usually from the back of the cylinder head to the firewall), remove it, and clean the contact points with a wire brush until they’re shiny. It’s a 10-minute check that can save you a huge headache.
Common Symptoms of a Failing ECM:
- โ Check Engine Light is on with communication-related codes (U-codes) or multiple random sensor codes.
- โ Engine cranks but refuses to start.
- โ Unexplained stalling or hesitation while driving.
- โ Noticeable drop in fuel efficiency.
- โ Harsh or erratic automatic transmission shifting.
- โ Failure to pass an emissions test.
Plug-and-Play Installation: No Dealer Visit Required
Installing your new ECM is straightforward. We’ve taken care of the programming, so you just need to perform the physical swap. For most Silverado models, the process is simple:
- Safety First: Disconnect the negative battery terminal and wait a few minutes for the system to discharge.
- Locate the ECM: On your Silverado 3500, it’s typically found in the LH front of the engine compartment, near the battery or airbox.
- Disconnect the Harnesses: Carefully release the locking tabs on the electrical connectors and pull them straight out. Never force them. Inspect the pins for any corrosion or damage.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket.
- Install the New Module: Bolt your new, pre-programmed ECM into place.
- Reconnect Everything: Firmly reconnect the electrical harnesses until they click into place. Reconnect the negative battery terminal.
- Perform Security Relearn: You may need to perform a simple key-cycle security relearn procedure. Typically, this involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times before starting the engine. Your vehicle’s manual will have the specific instructions.
Guaranteed Compatibility
This module is a direct replacement for a wide range of GM vehicles and supersedes multiple part numbers. If your original module has any of the following numbers, this is the correct part for you:
Replaces Part Numbers: 12668866, 12668994, 12643636, 12663405, 12670335, 22819494, 12692200.
While this listing focuses on the 2012-2016 Silverado 3500 ECM for the 6.0L engine, it also fits a vast array of other GM models, including the Sierra 2500/3500, Express/Savana Vans, Cruze, Sonic, Volt, and more, ensuring a high-quality, tested solution for your vehicle. Please verify the fitment data provided to confirm it matches your specific make, model, and engine option.