Get Your Hummer Back on the Trail with a Reliable, Programmed ECM
There’s nothing more frustrating than an unreliable vehicle, especially when it’s as capable as a Hummer H3. If you’re dealing with a persistent check engine light, erratic engine behavior, or a vehicle that refuses to start, a failing Engine Control Module (ECM) is often the culprit. As the brain of your engine, a faulty ECM can cause a cascade of confusing problems. This isn’t just an inconvenience; it’s a critical failure that can leave you stranded. We provide a dependable solution: a high-quality replacement Hummer H3 ECM, professionally programmed with the latest GM software updates specifically for your vehicle’s VIN.
From the Diagnostic Bay: The Phantom Stall
I remember a customer bringing in his 2009 H3 with a problem that was driving him crazy. The truck would run perfectly for days, then suddenly stall at a stoplight with no warning. No codes were stored immediately. We checked fuel pressure, sensors, and wiring—everything looked fine. After a week of testing, it finally threw a P0606 (ECM/PCM Processor Fault) code just once. It was the ECM itself, failing intermittently under specific thermal conditions. Replacing the module with a properly programmed unit solved the issue permanently. These phantom problems are a classic sign of a failing Hummer H3 ECM, and a simple replacement is the definitive fix.
Common Signs of a Failing Engine Control Module
- ✔ Persistent Check Engine Light (CEL) that won’t clear.
- ✔ Diagnostic Trouble Codes (DTCs) pointing to internal module failure, such as P0601, P0606, or U0100.
- ✔ Engine stalling, stumbling, or misfiring for no apparent reason.
- ✔ Complete no-start condition where the engine cranks but won’t fire up.
- ✔ Poor fuel economy and a noticeable loss of power.
- ✔ Issues with automatic transmission shifting, as the ECM communicates with the TCM.
A Straightforward Guide to Installation
Replacing the ECM on your H3 is a manageable job for a DIYer with basic tools. Our pre-programming service saves you a trip to the dealership. Follow these general steps for a successful installation:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 15 minutes for the system capacitors to discharge.
- Locate the ECM: On the 2009-2010 Hummer H3, the ECM is typically located on the right-hand (passenger) side of the firewall in the engine bay.
- Disconnect and Remove: Carefully unplug the electrical connectors. They have locking tabs that need to be released. Once disconnected, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new ECM into place and securely reconnect the wiring harnesses. Ensure they click into place.
- Reconnect Battery: Reattach the negative battery terminal.
- Perform Security and CASE Relearn: After installation, a security relearn procedure and a Crankshaft Variation (CASE) relearn are required for the vehicle to start and run correctly. This can be done with a capable bi-directional scan tool. This step is critical for proper engine operation and cannot be skipped.
Verified Vehicle Compatibility
This ECM, part number 12628993, is a direct replacement for a wide range of GM vehicles. We program it based on the VIN you provide to ensure perfect compatibility. It is interchangeable with service numbers 12636659, 12639300, 1263605, 12628911, 12625453, 12622175, 12630464, and 12678512 and fits the following models:
- HUMMER H3: 2009, 2010 (3.7L)
- Cadillac CTS: 2009 (6.2L)
- Cadillac DTS: 2009-2011
- Cadillac SRX: 2009 (4.6L)
- Cadillac STS: 2009 (4.4L, 4.6L), 2010 (4.6L)
- Cadillac XLR: 2009
- Chevrolet Colorado: 2009, 2010-2012 (2.9L, 3.7L)
- Chevrolet Corvette: 2009 (ZR1)
- Chevrolet Trailblazer: 2009 (6.0L)
- GMC Canyon: 2009, 2010-2012 (2.9L, 3.7L)
- GMC Envoy: 2009 (5.3L)
- Buick Lucerne: 2009-2011 (4.6L)
- SAAB 9-7X: 2009
Your Solution for a Lasting Repair
Don’t let a faulty computer keep your truck off the road. This replacement Hummer H3 ECM is your path to restoring factory performance and reliability. By providing us with your VIN, you receive a module that is not just a part, but a complete, ready-to-install solution with the most current software from General Motors.
Frequently Asked Questions
Why do you need my VIN?
Your Vehicle Identification Number (VIN) allows us to program the ECM with the exact software and calibrations for your H3’s specific engine, transmission, and options. This ensures seamless integration and proper function, eliminating the need for expensive dealership programming.
Is this a plug-and-play part?
Almost. While the module arrives programmed to your VIN, you will need to perform a security relearn and a CASE (Crankshaft Variation) relearn after installation. This is a standard procedure for GM vehicles and can be done with most professional-grade scan tools.
Will this fix my check engine light?
If the check engine light is caused by an internal failure of the original ECM (e.g., codes P0601, P0606), then yes, this part will resolve the issue. However, you must ensure that there are no other underlying problems with sensors or wiring that are causing the light.
What tools are needed for the CASE relearn?
A bi-directional scan tool is required for the CASE relearn procedure. Many local repair shops can perform this service for you if you do not own one. It is a quick but essential step.
My original part has a different service number. Will this still work?
Yes. Part number 12628993 is the base number for a family of modules. It is interchangeable with several other service numbers, including 12636659, 12639300, and others listed in the description. As long as your vehicle is on the compatibility list, we will program it to be a perfect match.