Is your 2005 Buick Allure, LaCrosse, or Pontiac Grand Prix suffering from frustrating and hard-to-diagnose engine problems? Issues like a persistent check engine light, rough running, stalling, or a complete no-start condition can often be traced back to a failing Powertrain Control Module (PCM), the central computer of your vehicle. This replacement PCM, part number 12591278 (interchangeable with 19210068), is the definitive solution to restore your vehicle’s performance, reliability, and drivability.
Unlike salvage yard units with unknown histories, this module is meticulously tested and programmed specifically for your car. Upon purchase, you simply provide us with your vehicle’s 17-digit VIN. Our technicians will then flash the module with the latest, most stable software updates directly from GM. This VIN-specific programming ensures that the PCM communicates perfectly with your vehicle’s engine, transmission, anti-theft system, and all other onboard electronics, just as the original did from the factory.
We had a 2005 Pontiac Grand Prix with the 3.8L V6 come into the shop with a maddening, intermittent stalling issue and a P0601 Internal Control Module Memory Check Sum Error code. The owner had already replaced the battery, alternator, and crankshaft position sensor trying to solve the problem. After confirming power and grounds to the PCM were solid, we knew the internal processor was failing. We installed one of our VIN-programmed modules, performed the 10-minute security relearn procedure, and the car fired up instantly. The stalling was gone, and the check engine light stayed off. It’s a classic case where chasing sensors can cost hundreds, when the root cause is the vehicle’s computer itself.
Common Symptoms of a Failing PCM
- ✔ Persistent Check Engine Light with communication-related or internal processor fault codes.
- ✔ Unexplained engine stalling or stumbling, especially when warm.
- ✔ Noticeable decrease in fuel efficiency.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Engine misfires or hesitation during acceleration.
- ✔ Complete no-start condition where the engine cranks but will not fire.
- ✔ Inability for diagnostic scan tools to communicate with the module.
The Importance of a VIN-Programmed 2005 Allure PCM
The PCM in your GM vehicle is more than just a simple component; it’s the brain. It manages critical functions like fuel injector timing, ignition coil firing, transmission shift points, and emissions systems. A generic, non-programmed module simply will not work. It lacks the specific software required for your car’s unique configuration, including its anti-theft system (Passlock/Passkey). Our service eliminates the guesswork and the need for expensive dealership programming. We handle the complex flashing process for you, so you receive a part that is ready for installation and a simple security relearn procedure, which you can often do yourself right in your driveway.
This module is a direct-fit replacement for the following vehicles equipped with the 3.8L V6 engine:
- 2005 Buick Allure
- 2005 Buick LaCrosse
- 2005 Pontiac Grand Prix
Please Note: After installation, you will likely need to perform a Security Relearn Procedure to sync the new PCM with your vehicle’s anti-theft system. This procedure typically involves turning the key to the ‘ON’ position for 10-12 minutes, then off, and repeating two more times. A Crankshaft Variation (CASE) Relearn may also be required with a capable scan tool to prevent a P1336 trouble code, though the vehicle will still run and drive without it.
Frequently Asked Questions
Is this PCM truly plug-and-play?
It is physically plug-and-play, meaning it will connect to your existing wiring harness without modification. Because we pre-program it to your VIN, it eliminates the need for dealership flashing. However, you will need to perform a security relearn procedure to sync the module with your keys, which is a simple process you can do at home.
How do I provide my VIN?
After you complete your purchase, please send us a message with your 17-digit Vehicle Identification Number (VIN). We cannot ship your order until we receive this information, as it’s essential for the programming process.
What is the difference between part numbers 12591278 and 19210068?
These are interchangeable GM part numbers for the same hardware. GM often updates part numbers over time. As long as your vehicle is a 2005 Allure, LaCrosse, or Grand Prix with the 3.8L engine, this module is the correct fit.
Will this fix my car’s problem for certain?
This part resolves issues directly caused by a faulty PCM. While the symptoms listed are very common for PCM failure, we always recommend a proper diagnosis by a qualified mechanic to confirm the PCM is the point of failure before ordering. We are not responsible for misdiagnosed vehicle issues.
What if I install it and my car doesn’t start?
The most common reason for a no-start after installation is an incomplete or improperly performed security relearn procedure. Please ensure you follow the steps carefully. If you’ve confirmed the relearn was done correctly and the vehicle still won’t start, check your battery connections and vehicle grounds, as these are also common culprits.