Restore Your HUMMER’s Brain and Get Back on the Trail
Is your 2009 or 2010 HUMMER H3 giving you headaches? Unexplained stalling, a persistent check engine light, or a frustrating no-start condition can often be traced back to a single component: the Engine Control Module (ECM). As the central computer of your vehicle, a faulty ECM can cause a cascade of problems that are difficult to diagnose. This isn’t just a replacement part; it’s a complete, reliable solution designed to restore your vehicle’s performance and dependability.
Over my 20+ years in the bay, I’ve seen countless owners and even other shops chase their tails replacing sensors and spark plugs, only to find the ECM was the root cause all along. We eliminate the guesswork and the expensive trip to the dealership. By providing us with your Vehicle Identification Number (VIN) during checkout, we will program this module with the latest official GM software specific to your H3. It arrives at your door ready for a straightforward installation, saving you hundreds in programming fees.
A Technician’s Notebook: The Intermittent H3 Stall
A customer brought in a 2010 HUMMER H3 with a problem that was driving them crazy. The truck would run perfectly for days, then suddenly stall at a stoplight and refuse to restart for 10-15 minutes. No consistent trouble codes were stored, just a few random communication errors. We checked fuel pressure, ignition components, and wiring harnesses—all were fine. On a hunch, I monitored the ECM data stream during a test drive. Right before it stalled, the data feed went haywire. The internal processor of the original ECM was failing under heat soak. We installed one of our pre-programmed modules, and the H3 has been running without a single issue for over a year. Sometimes, the simplest solution is the right one.
Is Your H3 Showing These Symptoms?
- ✔️ Engine cranks but refuses to start.
- ✔️ Unexplained stalling, especially when warm.
- ✔️ Drastic decrease in fuel economy.
- ✔️ Check Engine Light is on with communication codes (like U0100) or internal processor fault codes (like P0601, P0606).
- ✔️ Harsh or erratic automatic transmission shifting.
- ✔️ Failure to pass an emissions or smog test.
Your Straightforward Installation Guide
- ✔ Safety First: Always disconnect the negative terminal from your vehicle’s battery before beginning work.
- ✔ Locate the ECM: On the HUMMER H3, the ECM is typically located on the right-hand (passenger) side of the firewall in the engine bay.
- ✔ Disconnect Connectors: Carefully release the locking tabs and unplug the wiring harness connectors from the old module. Inspect them for any corrosion or damage.
- ✔ Remove Old Module: Unbolt the old ECM from its mounting bracket. Keep the hardware as you will need it for the new module.
- ✔ Install New Module: Mount your new, pre-programmed ECM onto the bracket and securely fasten it.
- ✔ Reconnect Everything: Plug the wiring harnesses back into the new module until they click securely in place. Reconnect the negative battery terminal.
- ✔ Final Step: In many cases, a security relearn procedure may be required for the vehicle to start. This procedure is simple and typically involves turning the key to the ‘ON’ position for 10-15 minutes. Instructions are readily available online or in your owner’s manual.
This module is a direct replacement for service part number 12628993 and is also interchangeable with the following part numbers: 12636659, 12639300, 1263605, 12628911, 12625453, 12622175, 12630464, and 12678512. Getting the correct, properly programmed 2009-2010 HUMMER H3 ECM is critical for a lasting repair.
Verified Vehicle Compatibility
While this is the primary module for the H3, its versatile design allows it to be programmed for a wide range of GM vehicles. Please confirm your vehicle is on this list:
- CADILLAC CTS (2009)
- CADILLAC DTS (2009-2011)
- CADILLAC SRX (2009)
- CADILLAC STS (2009-2010)
- CADILLAC XLR (2009)
- CHEVROLET COLORADO (2009-2012)
- CHEVROLET CORVETTE (2009)
- CHEVROLET TRAILBLAZER (2009)
- GMC CANYON (2009-2012)
- GMC ENVOY (2009)
- HUMMER H3 (2009-2010)
- BUICK LUCERNE (2009-2011)
- SAAB 9-7X (2009)
Frequently Asked Questions
Do I need to get this programmed by a dealer?
No. We handle all the programming for you before we ship the part. Just provide your vehicle’s VIN at checkout, and it will arrive ready to install.
What is a VIN and where do I find it?
The VIN is your vehicle’s unique 17-digit identification number. You can find it on your driver’s side dashboard (visible through the windshield), on the driver’s side door jamb sticker, or on your vehicle’s registration and insurance documents.
Will I need to perform any other procedures after installation?
You may need to perform a simple security relearn procedure, also known as a Passlock or anti-theft relearn. This can typically be done without any special tools and involves a sequence of key turns. This syncs the new ECM with your vehicle’s security system.
My old part has a different service number. Will this still work?
Yes. This module is a direct replacement for a wide range of service numbers, including 12636659, 12639300, and others listed above. As long as your vehicle model and year are listed, we will program it to function correctly.
Is this a difficult part for a DIYer to replace?
For someone with basic mechanical skills, this is a very manageable job. The ECM is usually easy to access on the firewall, and the replacement involves simple hand tools. The biggest benefit is that our pre-programming removes the most complex part of the job.