Is Your Duramax Diesel Running Rough? Get Back on the Road Fast.
There’s nothing more frustrating than a powerful GM truck or van that won’t run right. Whether you’re dealing with a no-start condition, erratic engine behavior, or a persistent Check Engine Light that points to a faulty engine computer, a failing Engine Control Module (ECM) can bring your workhorse to a dead stop. This module is the brain of your LLY Duramax engine, controlling everything from fuel injection and timing to turbo boost and emissions. When it fails, you need a reliable, direct-fit solution that works right out of the box. This is that solution.
This is a replacement ECM, part number 12606126, for a wide range of 2006-2007 GM trucks and vans equipped with the LLY Duramax diesel engine. We take the guesswork and hassle out of the replacement process. Simply provide us with your vehicle’s VIN (Vehicle Identification Number) during checkout, and our technicians will program the module with the latest, most stable software updates directly from GM. This ensures perfect compatibility and optimal performance for your specific vehicle, eliminating the need for an expensive trip to the dealership for programming.
Common Symptoms of a Failing LLY Duramax ECM
- ✔ Check Engine Light is on with communication-related trouble codes (e.g., U-codes).
- ✔ Engine cranks but will not start.
- ✔ Poor fuel economy or a noticeable loss of power.
- ✔ Intermittent stalling or stumbling while driving.
- ✔ Harsh or incorrect transmission shifting patterns.
- ✔ Communication issues with diagnostic scan tools.
- ✔ Injector balance rates are erratic or out of specification.
Expert Pro Tip
Before condemning your ECM, always perform a thorough inspection of your vehicle’s main ground connections, especially the one from the battery to the engine block and frame. Also, carefully inspect the large wiring harness that connects to the FICM (Fuel Injection Control Module), as chafing on nearby brackets is a very common issue on these trucks that can cause symptoms identical to a failing ECM. A few minutes of inspection can save you from replacing a part that isn’t faulty.
The Plug-and-Play Solution for Your GM Diesel
Replacing an engine computer can seem daunting, but we make it straightforward. Because this LLY Duramax ECM is pre-programmed to your VIN, the most complex part of the job is already done. Installation is as simple as disconnecting the battery, swapping the old module with the new one, and reconnecting the battery. After installation, you will need to perform a simple security relearn procedure, also known as the Passlock or VATS relearn, which pairs the new ECM to your vehicle’s anti-theft system. This procedure requires no special tools and can be done in your own driveway.
Simple Security Relearn Procedure (No Tools Required):
- Install the new ECM and connect the battery.
- Attempt to start the engine. It will likely start and then immediately stall. The security light may illuminate.
- Leave the key in the “ON” position (not accessory, but with the dash lights on) for 10-12 minutes. The security light should turn off or stop flashing.
- Turn the key to the “OFF” position for 10 seconds.
- Repeat steps 3 and 4 two more times for a total of three 10-minute cycles.
- After the third cycle, turn the key off, wait 10 seconds, and then the vehicle should start and run normally.
This module is a direct replacement for multiple part numbers, ensuring wide compatibility. It fits part numbers: 19260753, 12588335, 12606126, 12606127, 12603623, 12604137, and YNAY. It is designed to fit the following vehicles with the 6.6L LLY Duramax Diesel engine (VIN 2, 8th digit):
- 2006-2007 Chevrolet Express 2500/3500
- 2006-2007 GMC Savana 2500/3500
- 2006-2007 Chevrolet Silverado 2500/3500 (including ’07 Classic)
- 2006-2007 GMC Sierra 2500/3500 (including ’07 Classic)
Frequently Asked Questions
Do I need to get this ECM programmed by a dealer?
No. We handle all the programming for you before we ship the part. Just provide your vehicle’s VIN at checkout, and it will arrive ready for installation and the security relearn procedure.
Where is the ECM located on my truck?
The location varies slightly by model. On Silverado and Sierra pickups, it is typically found on the driver’s side, under the battery tray. On Express and Savana vans, it is located in the driver’s side rear engine compartment.
Will this fix my transmission shifting problems?
It can. The ECM works directly with the Transmission Control Module (TCM) to control shift points. If the ECM is sending faulty data, it can cause erratic shifting. However, shifting issues can also be caused by the TCM itself, solenoids, or internal transmission components, so a proper diagnosis is always recommended.
Is any other work required after installation?
Besides the security relearn procedure detailed above, no other work is required. In some rare cases, a Crankshaft Position Variation (CASE) relearn may be needed to turn off the check engine light, which can be performed with a capable bi-directional scan tool.
How do I find my VIN?
Your 17-digit VIN can be found on your vehicle’s registration, insurance card, or on the driver’s side of the dashboard, visible through the windshield.