Is Your 6.6L Duramax Running Rough, Stalling, or Not Starting at All?
If your GM workhorse truck or van is experiencing frustrating engine problems, a faulty Engine Control Module (ECM) is a very likely culprit. As a technician with over two decades of experience under the hood of these vehicles, I’ve seen firsthand how a failing ECM can cause a cascade of issues, from erratic idling and poor fuel economy to a complete no-start situation that leaves you stranded. This isn’t just an inconvenience; it’s lost time and money. This genuine, used OEM ECM, part number 12654088, is the reliable and cost-effective solution to get your vehicle back on the road and running as it should.
The Brain of Your Duramax, Programmed Specifically for You
Don’t risk installing a blank module that requires expensive and time-consuming dealer programming. We take the guesswork out of the repair. Before this ECM ships, we will flash it with the latest official GM calibrations for your specific vehicle. All you need to do is provide us with your Vehicle Identification Number (VIN) at checkout. This ensures the ECM communicates perfectly with your truck’s other systems, like the transmission controller and instrument cluster, right out of the box.
Expert Pro Tip: Check Your Connectors First!
Before you condemn your old ECM, take a moment to disconnect the main wiring harnesses and inspect the pins on both the module and the connectors. On these work trucks and vans, I’ve often traced ECM-like symptoms to a single corroded or bent pin caused by moisture or vibration. A quick spray with electrical contact cleaner and careful inspection can sometimes save you the cost of a replacement part. If the pins look clean and straight, you can proceed with the replacement confidently.
Common Symptoms of a Failing 2013-2014 Express 3500 ECM:
- โ Check Engine Light is on with various communication or sensor codes.
- โ Vehicle cranks but will not start.
- โ Noticeable loss of engine power and poor acceleration.
- โ Decreased fuel efficiency.
- โ Rough or inconsistent idling.
- โ Stalling or cutting out while driving.
Installation and Required Procedures
Replacing the ECM is a straightforward process, but it’s critical to follow the correct steps to ensure success. This part is designed for a direct fit, but post-installation steps are required.
- Safety First: Always disconnect the negative battery terminal and wait at least 15 minutes for the system to discharge before beginning work.
- Locate the ECM: On Express/Savana vans, it’s typically on the driver’s side rear of the engine compartment. On Sierra/Silverado trucks, it’s on the driver’s side front of the engine compartment.
- Disconnect and Remove: Carefully unplug the wiring harnesses and unbolt the old ECM from its mounting bracket.
- Install the New ECM: Mount your new, pre-programmed ECM and securely reconnect the wiring harnesses. Ensure they click into place.
- Reconnect Battery: Reattach the negative battery terminal.
- CRITICAL: Perform Vehicle Theft Deterrent Relearn: This is the most important step. If the vehicle does not start, you or your mechanic MUST perform the security relearn procedure using a professional scan tool with access to GM’s TIS2Web programming system. This synchronizes the new ECM with your vehicle’s anti-theft system.
- Additional Relearns: Depending on your vehicle’s specific needs, other procedures like a Crankshaft Variation Relearn or Injector Flow Rate programming may be necessary to achieve optimal performance. This is the responsibility of the installer.
Guaranteed Fitment for Your GM 6.6L Diesel
This ECM is a direct replacement for service numbers 12654088 and 12653319 and fits a wide range of GM HD trucks and vans equipped with the 6.6L Duramax engine. Please verify your part number and check the detailed fitment list to ensure compatibility.