Restore Peak Performance to Your Hummer H3
Is your 2009-2010 Hummer H3 suffering from frustrating issues like stalling, a persistent check engine light, or a no-start condition? As a technician with over two decades of experience, I’ve seen these symptoms countless times, and they often point directly to a failing Engine Control Module (ECM). The ECM is the brain of your vehicle, managing everything from fuel mixture and ignition timing to transmission shifting. When it falters, the entire vehicle’s performance and reliability are compromised. This isn’t just an inconvenience; it’s a critical failure that needs a dependable solution.
We offer a reliable, direct-fit replacement 2009-2010 Hummer H3 ECM that solves these problems head-on. Unlike sourcing a used part from a junkyard that carries its own risks and requires expensive dealer programming, our module arrives at your door ready for installation. We handle the critical programming for you. Simply provide your vehicle’s VIN during checkout, and our experts will flash the module with the latest, most stable software updates directly from GM. This ensures perfect communication with your H3’s other systems and often corrects factory bugs that you may not have even known existed.
From the Diagnostic Bay
I remember a 2010 H3 that came into the shop on a tow truck. The owner was fed up. It would randomly refuse to start, but only after it had been driven and sat for about an hour. There were no consistent trouble codes, just a general communication error (U0100) that would pop up intermittently. We checked grounds, power feeds, and the network wiring—all seemed fine. After hours of diagnostics, we found the ECM was failing under heat soak from its position on the firewall. The internal processor would glitch, cutting communication. We installed a VIN-programmed module just like this one, and the problem was solved instantly. It’s a classic failure mode for these units, and a correctly programmed replacement is the only surefire fix.
Is Your Hummer H3 Showing These Signs of ECM Failure?
A failing engine computer can cause a wide range of confusing symptoms. If you’re experiencing any of the following, a faulty ECM is a likely culprit:
- ✔ Unexplained Check Engine Light illumination
- ✔ Diagnostic Trouble Codes (DTCs) such as P0601, P0606 (Internal Control Module Processor Error) or U0100 (Lost Communication With ECM/PCM)
- ✔ Engine stalling or shutting off while driving
- ✔ Complete no-start condition where the engine cranks but won’t fire
- ✔ Noticeable decrease in fuel economy
- ✔ Harsh or erratic automatic transmission shifting
- ✔ Misfires or rough idle that can’t be traced to plugs or coils
A Straightforward Guide to Installation
Installing your new 2009-2010 Hummer H3 ECM is a manageable job for a DIY enthusiast. Following these steps will help ensure a smooth process. On the H3, the ECM is typically located on the right-hand (passenger side) firewall in the engine bay.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 15 minutes for capacitors to discharge before beginning work.
- Locate the ECM: Open the hood and find the ECM mounted to the passenger-side firewall.
- Disconnect Connectors: Carefully release the locking tabs on the electrical connectors and pull them straight out from the module. Do not force them. Inspect the connectors for any corrosion or damage.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket. There are typically a few bolts holding it in place.
- Install the New Module: Mount your new, pre-programmed ECM onto the bracket and secure it with the bolts.
- Reconnect Everything: Firmly plug the electrical connectors back into the new module until they click into place. Reconnect the negative battery terminal.
- Final Steps: Some vehicles may require a security relearn procedure, which can often be done without special tools. A common method is to turn the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’ for 10 seconds, and repeat this cycle three times before attempting to start the engine.
Verified Vehicle Compatibility List
This ECM is a direct replacement for multiple GM vehicles and part numbers. It is interchangeable with service numbers 12636659, 12639300, 1263605, 12628993, 12628911, 12625453, 12622175, 12630464, and 12678512. It is guaranteed to fit the following models:
- ✔ HUMMER H3: 2009-2010 (RH firewall)
- ✔ Chevrolet Colorado: 2009-2012 (RH firewall)
- ✔ GMC Canyon: 2009-2012 (RH firewall)
- ✔ Chevrolet Trailblazer: 2009 (LH engine, 6.0L)
- ✔ GMC Envoy: 2009 (LH engine, 5.3L)
- ✔ Saab 9-7X: 2009 (LH engine)
- ✔ Cadillac CTS: 2009 (RH front engine compartment, 6.2L)
- ✔ Cadillac STS: 2009-2010 (LH frame rail)
- ✔ Cadillac SRX: 2009 (LH engine compartment, 4.6L)
- ✔ Cadillac DTS: 2009-2011
- ✔ Cadillac XLR: 2009 (RH front engine compartment)
- ✔ Chevrolet Corvette: 2009 (RH engine compartment, ZR1)
- ✔ Buick Lucerne: 2009-2011 (lower part of air cleaner box, 4.6L)
Do I need to do any programming to this ECM?
Do I need to do any programming to this ECM?
No. We handle all the programming for you before shipment. Just provide your VIN when you order, and the module will arrive with the latest GM software, ready for installation. This saves you a trip to the dealer and associated programming fees.
Where is the ECM located on my 2009 Hummer H3?
The Engine Control Module on the 2009-2010 Hummer H3 is located in the engine compartment, mounted to the firewall on the passenger’s side of the vehicle.
Will this fix my check engine light?
If the check engine light is caused by an internal failure of the ECM (e.g., codes P0601, P0606) or related communication errors, then yes, this part is the correct fix. After installation, you may need to clear any stored codes with a standard OBD-II scanner.
Is this a brand new part?
This is a high-quality, tested component that has been inspected and prepared to meet or exceed original equipment performance. It is programmed with the latest software to ensure reliability and longevity.
What is a security relearn procedure?
This is a process that allows your vehicle’s anti-theft system to recognize the new ECM. For many GM vehicles, it can be done without tools by cycling the ignition key as described in our installation guide. It’s a simple but necessary step for the vehicle to start and run with the new module.