Is Your HUMMER H3 Running Rough, Stalling, or Refusing to Start?
As a technician with over two decades of experience, I know the frustration of a vehicle that won’t cooperate. When a 2009 or 2010 HUMMER H3 starts acting up with bizarre electrical issues, a persistent check engine light, or intermittent stalling, the root cause is often a failing Engine Control Module (ECM). This isn’t just an inconvenience; it’s the brain of your engine, and when it fails, your rugged H3 is sidelined.
Expert Pro Tip: Check Your Connectors First!
Before you even unbolt the old ECM from the firewall, take a bright light and carefully inspect the harness-side electrical connectors. Over the years, moisture and dirt can cause subtle corrosion on the pins. A quick spray with a quality electronics cleaner and a gentle scrub with a small brush can sometimes resolve communication errors. A clean connection is critical for your new module to function correctly from the moment you plug it in.
The Direct-Fit Solution: Your 2009–2010 HUMMER H3 ECM
Forget expensive dealership diagnostics and programming fees. This is a genuine, fully tested Engine Control Module, part number 12639300, that arrives at your door completely programmed and ready for installation. We take your vehicle’s unique Vehicle Identification Number (VIN) at checkout and flash the module with the latest, most stable software updates directly from GM. This ensures perfect communication with your H3’s other systems, right out of the box.
Common Symptoms of a Failing H3 Engine Computer:
- ✔ Persistent Check Engine Light (CEL) with communication-related codes.
- ✔ Engine stalling unexpectedly or failing to start at all.
- ✔ Noticeable decrease in fuel economy and poor engine performance.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Communication errors with diagnostic scan tools.
Plug-and-Play Installation: No Dealer Visit Required
You can get your HUMMER back on the trail yourself. Installing this module is a straightforward process that requires basic hand tools. Here’s a simple guide to get it done:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait 10-15 minutes for the system capacitors to discharge.
- Locate the ECM: On the 2009-2010 HUMMER H3, the ECM is typically mounted on the right-hand (passenger side) of the engine bay firewall.
- Disconnect Connectors: Carefully release the locking tabs on the electrical wiring harnesses and pull them straight out from the module. Avoid pulling on the wires themselves.
- Remove the Old Module: Unbolt the mounting hardware holding the original ECM in place and remove it from the vehicle.
- Install the New Module: Mount your new, pre-programmed ECM in the same location. Securely reconnect the wiring harnesses, ensuring they click into place.
- Reconnect Battery: Reattach the negative battery terminal. Your H3 is now ready to start with its new, fully updated engine computer.
Guaranteed Compatibility & Peace of Mind
This ECM is a direct replacement for a wide range of GM vehicles and is interchangeable with several service numbers. If your original module has any of the following numbers, this part is the correct fit for you:
Interchangeable Part Numbers: 12636659, 12639300, 1263605, 12628993, 12628911, 12625453, 12622175, 12630464, 12678512.
By providing your VIN, you guarantee that you are receiving a module programmed specifically for your H3’s engine, transmission, and factory options. This is the most reliable and efficient way to solve complex ECM-related issues and restore your vehicle’s factory performance. Order today and take control of your repair.