Is Your HUMMER H3 Running Rough, Stalling, or Refusing to Start?
As a technician with over two decades of experience, I’ve seen countless vehicles sidelined by a faulty Engine Control Module (ECM). For HUMMER H3 owners, the symptoms are often frustratingly clear: a sudden check engine light, erratic engine behavior, poor fuel economy, or a complete no-start condition that leaves you stranded. The ECM is the brain of your engine, and when it fails, it can cause a cascade of problems that are often misdiagnosed. This isn’t just an inconvenience; it’s a critical failure that compromises your vehicle’s performance and reliability.
The Direct Solution: A VIN-Programmed Engine Control Module
Forget about expensive dealership visits and the hassle of coordinating programming. This Engine Control Module, service number 12628911, is the straightforward, reliable fix you need. We take the guesswork out of the repair by pre-programming the module specifically for your vehicle using your VIN. This means it arrives at your door with the latest GM factory software updates already installed, ensuring seamless communication with your H3’s other systems right out of the box. It’s a true plug-and-play solution designed to get you back on the road quickly and confidently.
Expert Pro Tip: Check This Before You Replace
In my shop, I’ve seen customers ready to spend hundreds on an ECM when the real culprit was a simple, overlooked issue. Before condemning your 2009-2010 HUMMER H3 ECM, locate the main engine-to-chassis ground strap. On many GM trucks, it’s a braided cable near the engine block. Over time, these can corrode or become loose, causing voltage drops and communication errors that perfectly mimic a bad computer. A quick inspection and cleaning with a wire brush can sometimes save you the entire cost of a repair. If the ground is solid and your symptoms persist, the ECM is the next logical step.
Common Symptoms of a Failing HUMMER H3 Engine Computer
- โ Check Engine Light is on with communication-related fault codes (e.g., U-codes).
- โ Engine cranks but will not start.
- โ Stalling intermittently while driving or at idle.
- โ Noticeable drop in fuel efficiency.
- โ Rough or inconsistent engine performance and shifting.
- โ The anti-theft or security light stays on, preventing startup.
Plug-and-Play Installation: No Dealer Visit Required
Replacing the ECM on your H3 is a manageable DIY job. The module is typically located on the right-hand (passenger side) firewall in the engine bay.
- Safety First: Disconnect the negative terminal from your vehicle’s battery and wait 10 minutes for the systems to discharge.
- Locate the ECM: Find the module on the passenger-side firewall. It will have several large electrical connectors attached.
- Disconnect Connectors: Carefully release the locking tabs on each wiring harness connector and pull them straight out. Never force them.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket.
- Install the New Module: Bolt your new, pre-programmed ECM into place.
- Reconnect Everything: Firmly plug in the wiring harness connectors until they click into place. Reconnect your negative battery terminal.
- Final Step: Your vehicle may require a security relearn procedure, which can typically be done without special tools by cycling the key. Instructions are widely available online for your specific model.
Guaranteed Compatibility & Service Numbers
This module is a direct replacement for a wide array of GM vehicles and is interchangeable with multiple service numbers, ensuring a perfect match. If your original module has any of the following part numbers, this unit will work for your vehicle:
12636659, 12639300, 1263605, 12628993, 12628911, 12625453, 12622175, 12630464, 12678512
While this listing focuses on the 2009-2010 HUMMER H3 ECM, it also fits models like the Chevrolet Colorado, GMC Canyon, Cadillac CTS, Corvette, and more, making it a versatile and reliable solution across the GM family.