Is your 6.6L Duramax-powered truck suddenly giving you trouble? If you’re dealing with frustrating issues like a no-start condition, intermittent stalling, poor fuel economy, or a dashboard lit up with warning lights, a failing Engine Control Module (ECM) is a likely culprit. As the brain of your engine, a faulty ECM can cause chaos, leaving you stranded. This is a reliable, tested replacement ECM, part number 12654088, designed to get your truck back to peak performance without the steep dealership price tag.
We take the guesswork out of the repair. Before this module ships, we program it with the latest GM software calibrations specifically for your vehicle using the VIN you provide. This ensures it communicates correctly with your truck’s other systems right out of the box. This is a genuine, used component sourced from a salvaged vehicle and thoroughly inspected for quality and function, offering a dependable and cost-effective solution.
A Technician’s Notebook: The Intermittent No-Start Nightmare
I had a 2014 Silverado 2500 in the bay that was a real head-scratcher. The owner said it would randomly refuse to start, with no crank and no communication with the engine module on the scan tool (a classic U0100 code). Other times, it would start and run perfectly. We checked all the basics—battery, grounds, and wiring harnesses—and found nothing. After hours of diagnostics, we noticed the fault only happened when the engine bay was hot. On a hunch, we carefully heated the ECM with a heat gun, and sure enough, the truck refused to start. A hairline crack on the circuit board was expanding just enough when hot to break a connection. Replacing the ECM with a quality-tested unit like this one solved the problem permanently. These intermittent issues are often the first sign of internal ECM failure.
Is Your Duramax Showing These Symptoms?
A failing ECM can manifest in various ways. If you’re experiencing any of the following, this module is the likely solution.
- ✔ Vehicle will not start or has a crank-no-start condition.
- ✔ Check Engine Light is on with internal module codes (e.g., P0601, P0606).
- ✔ Loss of communication with the scan tool or other modules (U-codes).
- ✔ Poor engine performance, hesitation, or misfiring.
- ✔ A significant, unexplained drop in fuel mileage.
- ✔ Erratic transmission shifting or other electronic issues.
Your Step-by-Step Installation Guide
Replacing the ECM is a manageable job for a DIYer with basic tools, but the final steps require a capable scan tool or access to GM’s service software.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work.
- Locate the ECM: On Sierra and Silverado pickups, the ECM is typically found in the front left (driver’s side) of the engine compartment. On Express and Savana vans, it’s located in the left rear of the engine compartment.
- Disconnect and Remove: Carefully unplug the large electrical connectors. They have locking tabs that need to be released. Once disconnected, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the replacement ECM into place and securely reconnect the electrical connectors, ensuring they click into place.
- Reconnect Battery: Reattach the negative battery terminal.
- Perform Relearn Procedures: This is a critical step. If the truck does not start, you must perform the Vehicle Theft Deterrent System (VATS) relearn using the GM TIS2Web programming system or a compatible high-end scan tool. Other procedures, like a crankshaft position variation relearn or injector flow rate programming, may also be necessary depending on your specific situation. This is the responsibility of the installer.
Guaranteed Fitment for Your GM Vehicle
This module, part number 12654088, is a direct replacement for service numbers 12654088 and 12653319. It is compatible with the following vehicles equipped with the 6.6L Duramax diesel engine:
- ✔ 2013-2014 Chevrolet Silverado 2500 / 3500
- ✔ 2013-2014 GMC Sierra 2500 / 3500 (including Denali)
- ✔ 2013-2014 Chevrolet Express 2500 / 3500 Van
- ✔ 2013-2014 GMC Savana 2500 / 3500 Van
Why do I need to provide my VIN?
Why do I need to provide my VIN?
Your Vehicle Identification Number (VIN) is essential because it allows us to program the ECM with the exact software and calibrations your truck needs. This ensures proper engine function, transmission shifting, and communication with other onboard systems. It’s a critical step for a successful repair.
What is a “theft relearn” and why is it required?
Why do I need to provide my VIN?
Your Vehicle Identification Number (VIN) is essential because it allows us to program the ECM with the exact software and calibrations your truck needs. This ensures proper engine function, transmission shifting, and communication with other onboard systems. It’s a critical step for a successful repair.
Can I perform the relearn procedures myself?
Why do I need to provide my VIN?
Your Vehicle Identification Number (VIN) is essential because it allows us to program the ECM with the exact software and calibrations your truck needs. This ensures proper engine function, transmission shifting, and communication with other onboard systems. It’s a critical step for a successful repair.
Is this a new part?
Why do I need to provide my VIN?
Your Vehicle Identification Number (VIN) is essential because it allows us to program the ECM with the exact software and calibrations your truck needs. This ensures proper engine function, transmission shifting, and communication with other onboard systems. It’s a critical step for a successful repair.
My original ECM has service number 12653319. Will this part work?
Why do I need to provide my VIN?
Your Vehicle Identification Number (VIN) is essential because it allows us to program the ECM with the exact software and calibrations your truck needs. This ensures proper engine function, transmission shifting, and communication with other onboard systems. It’s a critical step for a successful repair.