Restore Your Truck’s Core Performance and Reliability
As a technician with over two decades of experience, I know the frustration that comes when your workhorse truck starts acting up. A failing Engine Control Module (ECM) in your 2012-2016 Sierra 3500 Pickup can feel like a complex, expensive problem. It’s the brain of your engine, and when it malfunctions, you can face everything from a no-start condition to poor fuel economy and a constant, glaring check engine light. This isn’t just an annoyance; it’s a reliability issue that can leave you stranded.
This isn’t just a replacement part; it’s a direct solution. We provide a high-quality Engine Control Module, part number 12670335, that arrives at your door fully programmed to your truck’s specific Vehicle Identification Number (VIN). This critical step ensures that all factory settings for your engine, transmission, and emissions systems are correctly loaded. We flash it with the latest GM-authorized software, so you’re getting the most stable and efficient calibrations available. This eliminates the need for an expensive trip to the dealership for programming, saving you both time and money.
Case Study: The Ghost in the Machine
I remember a 2014 Sierra 3500 with the 6.0L that came into my bay with a truly frustrating intermittent issue. The owner complained of random stalling at low speeds and occasional hard starting. There were no consistent trouble codes, just a history of U0100 (Lost Communication with ECM/PCM) and some random misfire counts. We checked grounds, wiring harnesses, and power feeds for hours. Everything seemed fine. On a hunch, I monitored the 5-volt reference circuits from the ECM while tapping on the module itself. Sure enough, the voltage would flicker, causing the engine to stumble. A hairline crack on the internal circuit board was the culprit. Replacing the 2012-2016 Sierra 3500 ECM with a properly programmed unit solved the problem instantly. It’s a perfect example of how a faulty module can create ghost-like symptoms that are nearly impossible to trace without direct experience.
Is Your Truck’s Brain on the Fritz? Common ECM Failure Signs
A failing ECM can manifest in numerous ways. If your Sierra is experiencing any of the following, a faulty module could be the root cause. Look out for these common indicators:
- ✔ Check Engine Light is on with codes like P0601, P0606, or communication errors (U-codes).
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained drops in fuel efficiency.
- ✔ Rough idling, stalling, or engine hesitation.
- ✔ Apparent transmission shifting problems or harsh shifts.
- ✔ Misfire codes that persist even after replacing plugs, coils, and injectors.
- ✔ Cooling fans running constantly or not at all.
A Straightforward Guide to Your ECM Swap
Replacing the 2012-2016 Sierra 3500 ECM is a manageable job for a DIY enthusiast with basic tools. Because this module comes pre-programmed, you avoid the most complex part of the process. Just follow these general steps to get your truck back in top form.
- Safety First: Always disconnect the negative terminal from your truck’s battery and wait at least 10-15 minutes for the system capacitors to discharge.
- Locate the ECM: On most 2012-2016 Sierra/Silverado HD trucks with the 6.0L engine, the ECM is located in the front left (driver’s side) of the engine compartment, often near the battery or airbox.
- Disconnect the Connectors: Carefully release the locking tabs on the electrical connectors and pull them straight out from the module. Never force them. Inspect the pins for any corrosion or damage.
- Remove the Old Module: Unbolt the mounting hardware holding the old 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: Firmly plug the electrical connectors back into the new ECM until they click into place. Reconnect the negative battery terminal.
- Final Steps: In some cases, a security relearn or crank position sensor relearn may be required. This can often be done with a simple key-on/key-off procedure or with a capable scan tool. Your truck is now ready to start.
Verified Compatibility for Your GM Vehicle
This Engine Control Module is a direct replacement for part number 12670335 and other interchangeable part numbers listed below. While it is the correct module for the 2012-2016 Sierra 3500 ECM with the 6.0L gas engine, it also fits a wide range of other GM vehicles. Please confirm your part number or contact us with your VIN to ensure perfect fitment.
Primary Fitment:
- ✔ GMC Sierra 2500/3500 Pickup (2012-2016) – 6.0L Engine
- ✔ Chevrolet Silverado 2500/3500 Pickup (2012-2016) – 6.0L Engine
- ✔ GMC Savana 2500/3500 Van (2016) – 4.8L or 6.0L Engine
- ✔ Chevrolet Express 2500/3500 Van (2016) – 4.8L or 6.0L Engine
Also fits other models including: Buick Encore, Cadillac ELR, Chevrolet Cruze, Sonic, Spark, Trax, Volt, and more. Please see the detailed fitment list or provide your VIN for confirmation.
Interchangeable Part Numbers: 12668866, 12668994, 12643636, 12663405, 22819494, 12692200.
- Frequently Asked Questions
- Why do you need my VIN?
- Your Vehicle Identification Number (VIN) is essential for us to program the ECM with the exact software and calibrations your specific truck requires. This ensures perfect compatibility with your engine, transmission, and all factory-installed options.
- Is this part difficult to install?
- The physical installation is straightforward for most DIYers with basic tools. Since we handle the programming, you won’t need specialized computer equipment. Just swap the module and perform a simple security relearn if necessary.
- Will this fix my check engine light?
- If the check engine light is caused by an internal failure of the ECM (e.g., codes P0601-P0606), then yes, this will resolve the issue. However, you should always diagnose the codes first to ensure the problem isn’t a faulty sensor or wiring.
- What happens after I place the order?
- After you complete your purchase, you will need to send us your vehicle’s 17-digit VIN. We will program the module with the latest GM software updates matched to your VIN and then ship it to you, ready for installation.