Is Your Sierra 3500 Running Rough or Not Starting?
As a technician with over two decades of experience, I know that a failing Engine Control Module (ECM) on a workhorse like a 2012-2016 Sierra 3500 isn’t just an inconvenienceโit’s downtime that costs you money. When the brain of your engine starts to fail, you’ll see a host of frustrating and often confusing symptoms. Maybe your truck has an intermittent no-start condition, a persistent Check Engine Light with codes that don’t make sense, or it’s shifting erratically. These are classic signs that the ECM itself is the culprit.
This isn’t just another part. This is a complete, ready-to-install solution. We take a genuine OEM ECM, part number 12692200, and flash it with the latest GM-certified software specifically for your truck. All we need is your Vehicle Identification Number (VIN) at checkout. This means the module that arrives at your door is 100% plug-and-play, eliminating the need for an expensive trip to the dealership for programming.
Real-World Diagnostic Story
A customer’s 2014 Sierra 3500 with the 6.0L V8 was towed to my shop last month. It had a bizarre mix of U-series communication codes and a persistent misfire on cylinder 3 that wasn’t caused by the plug, wire, or injector. After checking the wiring, we traced the fault to a failed injector driver inside the original ECMโa common issue I’ve seen countless times from years of heat cycles and vibration. Swapping in a correctly programmed module like this one resolved all the issues instantly and had the truck back on the job site the same day.
Symptoms a Failing ECM Can Cause:
- โ Persistent Check Engine Light (CEL)
- โ Engine stalling or misfiring
- โ No-start or intermittent starting problems
- โ Poor fuel economy
- โ Harsh or incorrect transmission shifting
- โ Communication errors with other modules
- โ Failure to pass emissions testing
Plug-and-Play Installation: No Dealer Visit Required
Installing your new 2012-2016 Sierra 3500 ECM is a straightforward process you can do in your own driveway. This module is located in the front left (driver’s side) of the engine compartment.
- Safety First: Always disconnect the negative battery terminal and wait 10 minutes for the system to discharge completely.
- Locate the ECM: Find the module on the driver’s side of the engine bay, typically mounted near the battery or air filter box.
- Disconnect the Connectors: Carefully unlatch and remove the wiring harness connectors. Inspect them for any corrosion or bent pins before proceeding.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed ECM into place.
- Reconnect Everything: Firmly seat the wiring harness connectors until they click into place. Reconnect the negative battery terminal.
- Final Step: Your vehicle is now ready to start. In some cases, a security relearn procedure may be necessary, which can typically be done without special tools by cycling the key.
Guaranteed Compatibility
This ECM is a direct replacement for a wide range of GM vehicles and is guaranteed to function correctly if your original module carries any of the following part numbers:
Interchangeable Part Numbers: 12668866, 12668994, 12643636, 12663405, 12670335, 22819494, and 12692200.
While this listing is focused on the Sierra 3500, this versatile module also fits many other GM models including the Silverado 2500/3500, Express/Savana vans, Cruze, Sonic, Trax, Encore, and more. Please verify your part number or use the fitment chart to confirm compatibility.