Restore Peak Performance to Your 5.3L V8
Is your 2010 HUMMER H3 running rough, stalling unexpectedly, or flashing a persistent Check Engine Light? A failing Engine Control Module (ECM) is often the culprit behind these frustrating and hard-to-diagnose issues. As the ‘brain’ of your vehicle, the ECM governs everything from fuel injection and spark timing to transmission shifting. When it fails, performance suffers. This isn’t just an inconvenience; it can leave you stranded. This direct-fit ECM, part number 12678513, is the definitive solution to get your rugged H3 or other compatible GM vehicle operating reliably again.
We take the guesswork and high cost out of the equation. Unlike a generic module from a parts store, this ECM arrives at your door pre-programmed to your vehicle’s specific Vehicle Identification Number (VIN). Simply provide us with your VIN after purchase, and our technicians will flash the unit with the latest, most stable software updates from General Motors. This ensures seamless communication with your vehicle’s other modules and restores factory-level engine performance and fuel efficiency.
Is Your Vehicle Showing These Symptoms?
A faulty ECM can manifest in numerous ways. I’ve seen these modules cause intermittent issues that are a nightmare to diagnose. If you’re experiencing any of the following, a failing computer is a likely cause:
- ✔ Check Engine Light is on with codes like P0601 (Internal Control Module Memory Check Sum Error), P0606 (ECM/PCM Processor Fault), or U-series communication codes.
- ✔ Engine cranks but refuses to start.
- ✔ Unexplained drops in fuel economy.
- ✔ The engine misfires, stalls, or hesitates during acceleration.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Apparent loss of power, especially under load.
From the Diagnostic Bay
I remember a 2010 Colorado with the 5.3L—essentially the same powertrain as the H3—that came into my shop with a maddening problem. The owner said it would randomly stall at red lights, but only after driving for 30+ minutes on a hot day. There were no consistent codes, just a history of random misfires. We checked fuel pressure, sensors, and wiring, but everything looked perfect. On a hunch, I let the truck idle in the bay until it was fully heat-soaked and then aimed a heat gun at the ECM on the firewall. Within minutes, the engine sputtered and died. The internal processors were failing under thermal stress. A new, properly programmed 2010 Hummer H3 ECM (the same part number) fixed it permanently. Heat is the number one enemy of these modules.
A Straightforward Guide to Installation
Installing your new ECM is a job most DIYers can handle in under an hour with basic hand tools. This pre-programmed unit eliminates the need for expensive scan tools for initial setup.
- Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent accidental contact.
- Locate the ECM: On the HUMMER H3, Colorado, and Canyon, the ECM is typically mounted to the firewall on the right-hand (passenger) side of the engine bay.
- Disconnect Connectors: Carefully release the locking tabs on the wiring harness connectors and pull them straight out from the module. Inspect the pins for any corrosion or damage.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket. There are usually two or three bolts holding it in place.
- Install the New ECM: Mount your new, pre-programmed ECM onto the bracket and secure the bolts. Reconnect the wiring harnesses, ensuring they click securely into place.
- Reconnect Power: Reattach the negative battery terminal. The vehicle may require a security relearn procedure, which can often be completed by cycling the key. Consult your owner’s manual for specific steps.
Verified Vehicle Compatibility
This module is a direct replacement for service numbers 12678513 and 12633264. Please verify your vehicle’s options to ensure a perfect match.
- Cadillac CTS (2010-2013): 6.2L (Coupe, Sedan, Wagon)
- Cadillac CTS (2014-2015): 6.2L (Coupe, Sedan, Wagon)
- Chevrolet Camaro (2012): 3.6L or 6.2L (with ID 12633264)
- Chevrolet Camaro (2013-2015): 6.2L (VIN P, opt LSA)
- Chevrolet Colorado (2010-2012): 5.3L
- Chevrolet Corvette (2010-2013): 6.2L (VIN R or T, opt LS9)
- Chevrolet Malibu (2010-2012): 3.6L
- GMC Canyon (2010-2012): 5.3L
- HUMMER H3 (2010): 5.3L
Frequently Asked Questions
Do I really need to provide my VIN?
Yes, absolutely. Providing your VIN is critical. We use it to load the precise, vehicle-specific software and calibrations from GM. This step ensures your engine, transmission, and all related systems function correctly right out of the box.
Is this ECM truly plug-and-play?
For most vehicles, yes. Because it’s programmed to your VIN, it eliminates the need for a dealership-level programming tool. However, some GM vehicles may require a simple security or Crankshaft Variation (CASE) relearn procedure, which can often be done without special tools.
What is the difference between this and a used one from a junkyard?
A used ECM from another vehicle is locked to that vehicle’s VIN and options. It will not start or run your vehicle correctly without being completely wiped and reprogrammed, a service that dealerships charge hundreds for. Our module comes ready for your specific vehicle.
Will this fix my Check Engine Light?
If the Check Engine Light is caused by an internal failure of the ECM (like codes P0601, P0602, P0606), then this part is the correct fix. It is always best to have the codes professionally diagnosed to ensure the ECM is the root cause and not a faulty sensor or wire.
Where is the part number located on my original ECM?
The service number (like 12678513) is printed on a sticker on the case of your original ECM. You will need to access the module to view it.