Restore Peak Performance to Your Hummer H3
Is your 2009-2010 Hummer H3 suffering from frustrating and unpredictable issues like stalling, a persistent check engine light, or a complete no-start condition? As the central command center for your engine, a failing Engine Control Module (ECM) can cause a wide range of problems that can sideline your rugged vehicle. Over my 20+ years in automotive diagnostics, I’ve seen firsthand how a faulty ECM can mimic a dozen other issues, leading to wasted time and money on incorrect repairs. This replacement ECM is the direct, reliable solution to restore your H3’s engine management system to factory specifications.
The biggest hurdle in replacing an ECM has always been the expensive and time-consuming programming required at a dealership. We eliminate that step completely. When you purchase this module, you simply provide us with your vehicle’s 17-digit VIN. Our technicians will then program the unit with the latest, most stable GM software updates specific to your H3. It arrives at your door ready for a straightforward installation, getting you back on the road—or the trail—without the dealership hassle. This isn’t just a part; it’s a complete, ready-to-install solution for your 2009-2010 Hummer H3 ECM.
Case Study: A Tricky Diagnosis
A customer brought in a 2010 Chevy Colorado with the 3.7L engine—which uses this exact same ECM family—complaining of random stalling at stoplights. No codes were stored, and two other shops had already replaced the fuel pump and cleaned the throttle body with no success. During my diagnostic, I noticed the 5-volt reference signal to the sensors would flicker erratically right before a stall event. There were no wiring shorts. This pointed directly to an internal failure within the ECM’s processor. After installing a VIN-programmed module like this one, the voltage stabilized, and the stalling issue was completely resolved. This is a classic example of how an ECM can fail without setting a clear trouble code.
Is Your H3 Showing These Telltale Signs?
- ✔ Check Engine Light is on with codes like P0601 (Internal Control Module Memory Check Sum Error) or P0606 (ECM/PCM Processor Fault).
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained stalling, especially when coming to a stop or at idle.
- ✔ Noticeable decrease in fuel economy and poor engine performance.
- ✔ Misfires or rough running conditions.
- ✔ Your scan tool cannot communicate with the ECM.
- ✔ Intermittent electrical issues affecting gauges or other systems.
A Straightforward Guide to Installation
- ✔ Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent accidental reconnection.
- ✔ Locate the ECM: On the Hummer H3, the ECM is typically located on the right-hand (passenger side) of the firewall in the engine compartment.
- ✔ Disconnect Connectors: Carefully release the locking tabs on the electrical harness connectors and pull them straight out from the module. Avoid pulling on the wires themselves.
- ✔ Remove the Old Module: Unbolt the old ECM from its mounting bracket. Keep the hardware, as you will reuse it.
- ✔ Install the New Module: Mount your new, pre-programmed 2009-2010 Hummer H3 ECM onto the bracket and tighten the bolts.
- ✔ Reconnect Everything: Firmly plug the electrical connectors back into the new module until they click into place. Reconnect your negative battery terminal.
- ✔ Final Step: Turn the key to the ‘ON’ position (without starting) for 10-15 seconds to allow the systems to initialize before starting the engine. In most cases, no further security relearn is needed.
Verified Vehicle Compatibility List
This module is a direct replacement for service number 12628911 and is also interchangeable with part numbers 12636659, 12639300, 1263605, 12628993, 12625453, 12622175, 12630464, and 12678512. It fits the following vehicles:
- HUMMER H3 2009-2010 (Electronic Control Module; RH firewall)
- CADILLAC CTS 2009 (6.2L)
- CADILLAC DTS 2009-2011
- CADILLAC SRX 2009 (4.6L)
- CADILLAC STS 2009-2010 (4.4L, 4.6L)
- CADILLAC XLR 2009
- CHEVROLET COLORADO 2009-2012 (2.9L, 3.7L)
- CHEVROLET CORVETTE 2009 (ZR1)
- CHEVROLET TRAILBLAZER 2009 (6.0L)
- GMC CANYON 2009-2012 (2.9L, 3.7L)
- GMC ENVOY 2009 (5.3L)
- BUICK LUCERNE 2009-2011 (4.6L)
- SAAB 9-7X 2009
Frequently Asked Questions
Do I need to program this module?
No. We handle all the programming for you before shipment. Simply provide your vehicle’s VIN during checkout, and the module will arrive ready to install.
Where is the ECM on my 2009 Hummer H3?
The Engine Control Module is located in the engine bay, mounted to the firewall on the passenger’s side of the vehicle.
What is a VIN and why do you need it?
The VIN (Vehicle Identification Number) is a unique 17-digit code for your specific vehicle. We use it to load the exact factory software and calibrations for your H3’s engine, transmission, and options, ensuring perfect compatibility.
Will this part fix my check engine light?
If your check engine light is caused by an internal ECM failure (like codes P0601, P0602, P0606), this module is the correct fix. It’s crucial to properly diagnose the code first to ensure the ECM is the source of the problem.
Is this a difficult part to install myself?
For most DIYers with basic tools, this is a very manageable job. Since the programming is already done, it’s a matter of unplugging the old unit and plugging in the new one. The entire process typically takes less than 30 minutes.