Restore Your Buick’s Performance and Reliability
Is your 2009-2011 Buick Lucerne acting up? Frustrating issues like stalling, erratic engine behavior, or a persistent Check Engine Light can often be traced back to a failing Engine Control Module (ECM). As the brain of your vehicle, a faulty ECM can disrupt everything from fuel delivery to transmission shifting, making your car unreliable. This isn’t just an inconvenience; it’s a critical component for your car’s health and safety. I’ve spent two decades under the hood, and I’ve seen firsthand how a failing computer can mimic a dozen other problems, leading to wasted time and money on incorrect repairs.
This isn’t just a replacement part; it’s a complete, ready-to-install solution. We take the guesswork and dealer-level expense out of the equation. By providing your vehicle’s VIN at checkout, you’ll receive a professionally programmed 2009-2011 Lucerne ECM loaded with the latest GM software updates. This ensures perfect communication with your car’s existing systems, restoring the smooth, efficient performance you expect from your Buick.
A Technician’s Notebook: The Phantom Stall
A few months back, a 2010 Lucerne with the 4.6L V8 was brought to my shop. The owner was at his wit’s end. The car would run perfectly for 20-30 minutes, then suddenly stall at a stoplight and refuse to restart for at least an hour. He’d already replaced the fuel pump and crankshaft position sensor with no luck. No hard codes were stored, just a history of random communication faults. Knowing the ECM on these models sits in the lower air cleaner box, right above the hot transmission, I suspected a heat-soak issue. We monitored the ECM’s data stream on a long test drive. Sure enough, as engine bay temperatures peaked, the processor data went haywire right before it stalled. A new, properly programmed ECM fixed it for good. It’s a classic case where the symptoms don’t point directly to the computer, but experience tells you where to look.
Is Your Engine Computer Failing?
A bad ECM can cause a wide range of symptoms that are often misdiagnosed. If your Lucerne is experiencing any of the following, a failing computer is a likely culprit:
- ✔ 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 drops in fuel economy.
- ✔ The engine stalls, stumbles, or misfires intermittently.
- ✔ Automatic transmission shifts harshly or at the wrong times.
- ✔ Apparent loss of power and poor acceleration.
- ✔ Communication issues with diagnostic scan tools.
A Straightforward Guide to Installation
Replacing the ECM on your Lucerne is a job most DIYers can handle with basic tools. Our pre-programming service eliminates the most difficult step. Follow this general guide for a smooth 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 2009-2011 Lucerne with the 4.6L V8, the ECM is located within the lower portion of the air cleaner assembly. You will need to remove the top of the air box and the air filter to access it.
- Disconnect Connectors: Carefully unlatch and remove the electrical wiring harness connectors from the old ECM. Inspect the connectors for any corrosion or damage.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket within the air box housing.
- Install the New ECM: Mount your new, pre-programmed ECM in place and securely fasten it. Reconnect the wiring harnesses, ensuring they click firmly into place.
- Reassemble and Reconnect: Reinstall the air filter and air cleaner box lid. Reconnect the negative battery terminal.
- Perform Security Relearn: You may need to perform a simple key-cycle security relearn procedure. Turn the key to the ‘ON’ position for 10-15 minutes (do not start), then turn it ‘OFF’ for 10 seconds. Repeat this process 2-3 times to allow the vehicle’s anti-theft system to recognize the new ECM. Your car should then start normally.
Verified Vehicle Compatibility
This ECM, part number 12639300, is a direct replacement for a wide range of GM vehicles. It is interchangeable with service numbers 12636659, 1263605, 12628993, 12628911, 12625453, 12622175, 12630464, and 12678512. Please confirm your vehicle is on this list:
LUCERNE 09-11 Electronic Control Module; (lower part of air cleaner box), 4.6L
Cadillac:
CTS 09 Electronic Control Module; (RH front engine compartment), 6.2L
DTS 09-11 Electronic Control Module
SRX 09 Electronic Control Module; (LH engine compartment), (4.6L)
STS 09 Electronic Control Module; (LH frame rail), 4.4L or 4.6L
STS 10 Electronic Control Module; (LH frame rail), (4.6L)
XLR 09 Electronic Control Module; (RH front engine compartment)
Chevrolet:
COLORADO 09-12 Electronic Control Module
CORVETTE 09 Electronic Control Module; (RH engine compartment), ZR1
TRAILBLAZER 09 Electronic Control Module; (LH engine), 6.0L
GMC:
CANYON 09-12 Electronic Control Module
ENVOY 09 Electronic Control Module; (LH engine), 5.3L
Hummer:
HUMMER H3 09-10 Electronic Control Module; (RH firewall)
Saab:
SAAB 9-7X 09 Electronic Control Module; (LH engine)
Frequently Asked Questions
Frequently Asked Questions
Why do you need my VIN number?
Your Vehicle Identification Number (VIN) allows us to program the ECM with the exact software and calibrations specific to your Lucerne’s engine, transmission, and options. This ensures it works perfectly right out of the box, with no additional programming needed.
Is this a simple plug-and-play installation?
Yes, because we program the module to your VIN, it is a direct replacement. In most cases, you will only need to perform a simple security relearn procedure with your key, which takes about 30 minutes and requires no special tools.
Will this fix my car’s specific problem?
This module will correct any issues directly caused by a faulty ECM. While we cannot diagnose your vehicle remotely, the symptoms listed above are strong indicators of ECM failure. This part is the definitive fix for a bad computer.
What if my original part number is not 12639300?
This ECM is a direct replacement for several service numbers, including 12636659, 12628993, and others listed in the compatibility section. As long as your vehicle and original part number are on our list, this module will fit and function correctly.
Do I need to return my old ECM?
No core charge is required for this purchase. You can keep or responsibly dispose of your old module.