Is your 2016 GMC Savana 3500 van running rough, throwing confusing check engine light codes, or failing to start reliably? These are classic signs of a failing Engine Control Module (ECM), the central computer that manages your vehicle’s engine performance, fuel economy, and emissions. A faulty ECM can bring your workhorse van to a standstill, costing you time and money. This replacement ECM, part number 12668991, is the definitive solution to restore your van’s factory performance and dependability.
Unlike a generic module from a parts store, this unit is professionally programmed specifically for your vehicle. Upon purchase, you will provide us with your van’s Vehicle Identification Number (VIN). We then flash the module with the latest, most stable software updates directly from General Motors. This critical step ensures that all engine parameters, transmission shift points, and security systems communicate flawlessly, just as they did when your van was new. This eliminates the need for an expensive trip to the dealership for programming.
Common Symptoms of a Failing ECM
- ✔ Persistent and unexplained Check Engine Light (CEL)
- ✔ Engine stalling, sputtering, or misfiring
- ✔ Noticeable decrease in fuel efficiency
- ✔ Difficulty starting the engine or no-start conditions
- ✔ Harsh or erratic automatic transmission shifting
- ✔ Failure to pass emissions testing
- ✔ Communication errors with diagnostic scan tools
From the Diagnostic Bay
We had a 2016 Express 3500 (which uses the same ECM) come into the shop with a bizarre, intermittent no-start condition. The owner, a contractor, was losing work because his van was unreliable. We checked all the usual suspects—battery, starter, fuel pump—and everything tested fine. Scan tools showed intermittent communication loss with the ECM. After swapping in a generic, unprogrammed module which caused more issues, we installed a VIN-programmed unit like this one. The van fired up on the first try. After the quick security relearn, all communication was stable, and the problem was solved. It’s a reminder that for these complex vehicle networks, having the correct, VIN-specific software isn’t just a feature; it’s a necessity.
Why Choose Our Programmed 2016 Savana 3500 ECM?
This isn’t just a replacement part; it’s a comprehensive solution. The ECM is the brain of your vehicle, and our service ensures that brain is perfectly matched to its body. By programming the module to your VIN, we account for all the specific options and calibrations your Savana 3500 was built with, from its engine size (4.8L or 6.0L) to its emissions equipment. This module is also a direct replacement for a wide range of other GM vehicles, including the Chevrolet Express, Silverado & Sierra HD pickups, Cruze, Sonic, and more, making it a versatile and reliable component.
This ECM is a direct fit for part numbers: 12668866, 12668994, 12643636, 12663405, 12670335, 22819494, and 12692200. Please verify your original part number or contact us with your VIN to confirm compatibility before ordering.
Installation Process
Installation is straightforward for a qualified technician or an experienced DIYer. After physically swapping the module, you will need to perform a security relearn procedure (often called an anti-theft relearn or Passlock relearn). This procedure syncs the new ECM with your vehicle’s existing keys and security system. This can typically be done without special tools and instructions are widely available online or in service manuals. In some cases, a Crankshaft Variation Relearn (CASE Relearn) may be required, which necessitates a capable bi-directional scan tool.
Frequently Asked Questions
What do I need to do after I purchase this ECM?
After you complete your purchase, you must provide us with your 17-digit Vehicle Identification Number (VIN). You can add it to the order notes or reply to our confirmation email. We cannot program and ship the module without your VIN.
Is this part truly plug-and-play?
It is pre-programmed to your VIN, which handles 90% of the work. However, you will still need to perform a security relearn procedure after installation to sync the module with your vehicle’s anti-theft system. This is a standard step for all GM ECM replacements.
Will this fix my transmission shifting problems?
In many cases, yes. The ECM works in conjunction with the Transmission Control Module (TCM) to control shift points and behavior. If the ECM is providing faulty data, it can cause erratic shifting. A new, correctly programmed ECM often resolves these communication-based transmission issues.
My original part number is slightly different. Will this still work?
This module replaces several part numbers, including 12668866, 12668994, and 12643636. If your number is on our cross-reference list, it is a compatible replacement. If you are unsure, please contact us with your VIN and original part number to confirm fitment.
Do I need to send my old ECM (core) back?
No core charge or return is required for this part. You can keep or responsibly dispose of your old module.