Restore Peak Performance to Your Hummer H3
Is your 2009 or 2010 Hummer H3 suffering from frustrating issues like a persistent check engine light, rough idling, stalling, or a no-start condition? These are classic signs of a failing Engine Control Module (ECM), the central computer that governs your vehicle’s engine performance, fuel economy, and emissions. A faulty ECM can turn your rugged, reliable H3 into an unpredictable machine. This direct-fit Engine Control Module, part number 1263605, is the definitive solution to restore your vehicle’s factory performance and reliability.
Common Symptoms of a Failing Hummer H3 ECM
If you’re experiencing any of the following problems, a failing ECM is a likely culprit. Proper diagnosis is key, but these symptoms are strongly associated with the engine’s computer.
- ✔ Check Engine Light: The light is illuminated, often with communication-related error codes (U-codes) or specific sensor codes that don’t resolve after replacing the sensor.
- ✔ Engine Stalling or Misfiring: Your H3 may stall unexpectedly while driving or at a stop. You might also notice random misfires or a rough, inconsistent idle.
- ✔ No-Start Condition: The engine cranks but refuses to start. This can happen if the ECM fails to control the fuel injectors or ignition coils properly.
- ✔ Poor Fuel Economy: A sudden and unexplained drop in your miles per gallon (MPG) can indicate the ECM is not managing the air-fuel mixture correctly.
- ✔ Shifting Problems (Automatic Transmission): The ECM communicates with the transmission control module. A faulty ECM can lead to harsh shifting, delayed engagement, or the transmission getting stuck in one gear.
- ✔ Intermittent Electrical Issues: Since the ECM is a central hub, its failure can cause bizarre, hard-to-trace electrical gremlins throughout the vehicle.
From the Diagnostic Bay
We had a 2009 Hummer H3 come into the shop with a problem that had stumped two other mechanics. The owner complained of random stalling, but only after the vehicle was fully warmed up and had been driven for at least 20 minutes. There were no consistent trouble codes, just a generic history code for a lost communication with the BCM. We checked all the wiring and grounds—they were perfect. On a hunch, we monitored the live data from the ECM. Everything looked normal until, like clockwork, after 25 minutes of driving, the fuel injector pulse width data started fluctuating wildly just before it stalled. The ECM was failing internally under heat soak. We installed a VIN-programmed module just like this one, and the H3 ran perfectly. It’s often these subtle, heat-related failures that point directly to the main computer.
The Plug-and-Play Solution: A Programmed 2009-2010 Hummer H3 ECM
Replacing an ECM isn’t just about swapping hardware. Modern vehicles require the module to be programmed specifically to the vehicle’s Vehicle Identification Number (VIN). This process ensures the ECM has the correct software for your H3’s specific engine, transmission, and options. It also allows it to communicate with the other modules in the vehicle, like the anti-theft system. Our service eliminates the need for an expensive trip to the dealership. When you order from us, we handle the complex programming for you.
Here’s how it works:
- Place your order for this ECM.
- Provide us with your vehicle’s 17-digit VIN during checkout.
- Our technicians will use official GM equipment to flash the module with the latest, most stable software update for your specific Hummer H3.
- We ship the fully programmed, plug-and-play module directly to you.
Installation is straightforward. Simply disconnect the battery, remove the old module, install the new one, and reconnect the battery. In most cases, no further procedures are required to get your vehicle running again.
Guaranteed Compatibility
This ECM is a direct replacement for a wide range of GM vehicles and is interchangeable with multiple service numbers. Please verify that your vehicle is on the list below. This unit replaces the following part numbers: 12636659, 12639300, 1263605, 12628993, 12628911, 12625453, 12622175, 12630464, and 12678512.
This part will fit these makes and models with these options:
- HUMMER H3 2009-2010 (Electronic Control Module; RH firewall)
- CANYON / COLORADO 2009-2012 (Electronic Control Module; RH firewall)
- CORVETTE 2009 (Electronic Control Module; RH engine compartment, ZR1)
- CTS 2009 (Electronic Control Module; RH front engine compartment, 6.2L)
- DTS 2009-2011 (Electronic Control Module)
- ENVOY 2009 (Electronic Control Module; LH engine, 5.3L)
- LUCERNE 2009-2011 (Electronic Control Module; lower part of air cleaner box, 4.6L)
- SAAB 9-7X 2009 (Electronic Control Module; LH engine)
- SRX 2009 (Electronic Control Module; LH engine compartment, 4.6L)
- STS 2009-2010 (Electronic Control Module; LH frame rail)
- TRAILBLAZER 2009 (Electronic Control Module; LH engine, 6.0L)
- XLR 2009 (Electronic Control Module; RH front engine compartment)
Frequently Asked Questions
What does an ECM do on my Hummer H3?
The Engine Control Module (ECM) is the main computer that controls all aspects of your engine’s operation. It takes data from sensors around the vehicle (like oxygen sensors and the throttle position sensor) and uses it to manage fuel injection, ignition timing, and variable valve timing to ensure optimal power, efficiency, and low emissions.
Do I need to program this module myself?
No. This is the primary benefit of our service. We program the ECM to your vehicle’s specific VIN before we ship it. This makes the installation process plug-and-play, saving you a trip to the dealer and the cost of their programming service.
Where is the ECM located on a 2009-2010 Hummer H3?
On the 2009-2010 Hummer H3, the ECM is typically located on the right-hand (passenger) side of the firewall in the engine compartment. Always disconnect the vehicle’s battery before attempting to remove or install the module.
What information do you need from me?
We only need your vehicle’s 17-digit Vehicle Identification Number (VIN). You can find this on your vehicle’s registration, insurance card, or on a plate on the driver’s side dashboard visible through the windshield. Please provide the VIN during checkout to avoid delays.
Is a security or key relearn procedure required after installation?
In most cases for this specific GM platform, our programming ensures the module is ready to go without any additional security procedures. However, in rare instances, a simple security relearn procedure (which can be done without special tools) may be necessary. Instructions can be easily found online or in a service manual.