Restore Your Vehicle’s Brainpower and Performance
Is your 2005 Chevrolet Uplander, Equinox, or another compatible GM vehicle suffering from frustrating and unpredictable issues? Problems like a persistent Check Engine Light, poor fuel economy, stalling, or harsh shifting often point to a single culprit: a failing Powertrain Control Module (PCM). The PCM is the central computer of your vehicle, managing everything from fuel injection and ignition timing to transmission shifting and emissions control. When it starts to fail, the symptoms can be widespread and difficult to diagnose. This genuine used GM PCM, part number 12591279, is the reliable and cost-effective solution to get your vehicle running smoothly again.
From the Diagnostic Bay
We had a 2005 Pontiac G6 come into the shop with a classic complaint: intermittent stalling at red lights and a check engine light that would come and go. The owner had already replaced the crankshaft position sensor and the MAP sensor based on codes he pulled, but the problem persisted. After hooking up our professional scan tool and monitoring live data, we saw erratic readings from multiple sensors that didn’t make sense. The voltage references were fluctuating. This is a classic sign that the PCM itself is the source of the problem, not the sensors it’s monitoring. We installed a VIN-programmed PCM like this one, performed a quick security relearn, and the G6 ran perfectly. It saved the customer from throwing more money at parts he didn’t need.
Is Your Vehicle Showing Signs of a Faulty PCM?
A failing engine computer can manifest in numerous ways. If you’re experiencing any of the following symptoms, a faulty PCM could be the root cause:
- ✔ Persistent Check Engine Light (CEL) on your dashboard.
- ✔ Unexplained drop in fuel efficiency.
- ✔ Engine stalling, sputtering, or misfiring.
- ✔ Difficulty starting the engine or a no-start condition.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Communication errors with diagnostic scan tools.
- ✔ Performance issues like hesitation or lack of power.
The Direct-Fit Solution: A Pre-Programmed 2005 Uplander PCM
Don’t let a complex computer issue keep you off the road. We make the replacement process straightforward. This isn’t just a part in a box; it’s a complete solution. When you order, you provide us with your vehicle’s 17-digit Vehicle Identification Number (VIN). Our technicians then use that VIN to flash the module with the latest, most up-to-date software directly from General Motors. This ensures that the computer is perfectly matched to your vehicle’s specific configuration, including its engine, transmission, and factory options. The result is a simple, plug-and-play installation that restores factory performance and functionality without requiring a trip to the dealership for expensive programming.
Guaranteed Compatibility and Functionality
This ECM is a direct replacement for part numbers 12591279 and 12591856. It is meticulously tested to ensure full functionality. Sourced from a salvaged vehicle, it offers a dependable and economical alternative to a new unit. It is compatible with a wide range of popular GM vehicles from the 2005-2006 model years. Please verify your part number and check the fitment list below to ensure this is the correct module for your vehicle.
This Electronic Control Module fits the following vehicles:
- 2005 Chevrolet Equinox (Located in LH engine compartment)
- 2005 Buick Relay (Located in LH engine compartment)
- 2006 Buick Relay (3.5L engine, Located in LH engine compartment)
- 2005 Chevrolet Malibu (New Body Style, VIN Z, 3.5L, Located in LH dash)
- 2005 Pontiac Montana (SV6, Located in LH engine compartment)
- 2005 Buick Terraza (Located in LH engine compartment)
- 2005 Pontiac G6 (Sedan, Located in LH front engine compartment)
- 2005 Chevrolet Uplander (Located in LH engine compartment)
Frequently Asked Questions
Why do you need my VIN?
Your Vehicle Identification Number (VIN) is essential for us to program the PCM correctly. The VIN contains critical information about your vehicle’s engine, transmission, emissions systems, and other factory-installed options. Programming the module with your VIN ensures it works seamlessly with your specific vehicle, just like the original unit did.
Is this part difficult to install?
For most of the listed vehicles, the PCM is located in the left-hand (driver’s side) of the engine compartment and is relatively easy to access. Installation typically involves disconnecting the battery, unplugging the electrical connectors from the old module, unbolting it, and then installing the new one in the reverse order. Basic hand tools are usually all that is required.
Will I need to do anything after installation?
In many cases, the vehicle will start and run perfectly after installation. However, some GM vehicles may require a simple, key-on/key-off procedure known as a “Security Relearn” or “CASE Relearn” to sync the new PCM with the vehicle’s anti-theft and crankshaft position systems. Instructions for these procedures are widely available online and typically do not require special tools.
Is this a new computer?
No, this is a high-quality, tested used part that has been sourced from a salvaged vehicle. Each unit is inspected to ensure it is in excellent working condition before being programmed and shipped. This provides a reliable and affordable alternative to a costly new module from a dealership.
How can I be sure this fits my vehicle?
The best way to ensure compatibility is to match the part number from your existing module to one of the numbers listed: 12591279 or 12591856. You can also use the detailed fitment list provided on this page. If you are still unsure, please contact us with your VIN, and we will be happy to verify the fitment for you.