Is Your 2005 Uplander Running Rough? The PCM Might Be the Culprit.
If your 2005 Chevrolet Uplander, or another compatible GM vehicle like the Equinox, Malibu, or Pontiac G6, is experiencing perplexing issues such as stalling, poor fuel economy, a persistent check engine light, or a no-start condition, the root cause is often the Powertrain Control Module (PCM). As the central computer of your vehicle, the PCM is responsible for managing everything from fuel injection and ignition timing to transmission shifting. When it begins to fail, it can create a cascade of problems that are often misdiagnosed, leading to costly and unnecessary repairs on other components.
This listing is for a genuine, used OEM Powertrain Control Module, part number 12591279 (interchangeable with 12591856). We take the guesswork and hassle out of the replacement process. Before this unit ships, we will program it with the latest GM software updates specifically for your vehicle using the VIN you provide. This ensures that when you receive the part, it’s ready for a straightforward installation, helping you get your vehicle back to its reliable, factory-spec performance quickly and affordably.
From the Diagnostic Bay
We had a 2005 Chevy Equinox come in on a tow truck. The owner had already replaced the fuel pump and crankshaft position sensor, but the vehicle would still randomly stall while driving and sometimes refuse to start. The check engine light was on with a slew of seemingly unrelated communication codes. After running a full diagnostic, we traced the network failures back to the source: a failing internal processor in the PCM. Instead of another expensive guess, we installed a VIN-programmed module just like this one. The vehicle started right up, all communication was restored, and the stalling issue was completely resolved. It’s a classic case where the “brain” was the problem, not the parts it was controlling.
Symptoms of a Failing 2005 Uplander PCM
A failing engine computer can manifest in various ways. If you’re noticing any of the following symptoms, it’s a strong indicator that your PCM may need replacement:
- ✔ Check Engine Light: The light is on, and you may have codes related to module communication errors (U-codes) or multiple sensor failures.
- ✔ Engine Stalling or Misfiring: The vehicle may stall unexpectedly while driving or at idle, and you might experience rough running or engine misfires.
- ✔ No-Start Condition: The engine cranks but refuses to start, even with a good battery and fuel supply.
- ✔ Poor Fuel Economy: A sudden and unexplained drop in your vehicle’s MPG can be caused by the PCM failing to properly manage the air-fuel mixture.
- ✔ Erratic Transmission Shifting: The PCM also controls transmission functions, so you might experience harsh shifts, delayed engagement, or getting stuck in a gear.
- ✔ Failed Emissions Test: An inability to pass an emissions or smog test is often directly linked to a malfunctioning engine computer.
The Right Part, Programmed for Your Vehicle
This isn’t just a used part pulled from a shelf. It’s a complete solution. By providing us with your vehicle’s VIN at checkout, you ensure that the module you receive is a direct, functional replacement for your original. Our programming service loads the correct software and calibrations for your Uplander’s specific engine, transmission, and options. This critical step prevents compatibility issues that would otherwise arise from installing a non-programmed computer. This unit has been carefully sourced from a salvaged vehicle and tested for functionality, offering a reliable and cost-effective alternative to a new dealership part.
Vehicle Fitment:
This Electronic Control Module is a direct fit for the following vehicles:
- 2005 Chevrolet Equinox (Located in LH engine compartment)
- 2005 Buick Relay (Located in LH engine compartment)
- 2006 Buick Relay (3.5L, Located in LH engine compartment)
- 2005 Chevrolet Malibu (New 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)
Please note: After installation, you may need to perform a security relearn procedure (often called a CASE relearn) with a capable scan tool to sync the new PCM with your vehicle’s anti-theft system and crankshaft position sensor. This is a standard procedure for GM vehicles of this era.
Frequently Asked Questions
Do I need to program this computer?
No. We handle the programming for you before shipment. Simply provide your vehicle’s 17-digit VIN during or after checkout, and we will flash the module with the latest GM software for your specific vehicle.
Is this a new part?
This is a high-quality, used OEM part sourced from a salvaged vehicle. Each unit is inspected and tested to ensure it is fully functional and ready for installation.
Where is the PCM located on a 2005 Uplander?
On the 2005 Chevrolet Uplander, the Powertrain Control Module (PCM) is typically located in the left-hand (driver’s side) of the engine compartment, often near the air filter housing or battery.
What is a CASE Relearn and will I need to do one?
A CASE (Crankshaft Angle Sensor Error) Relearn is a procedure that synchronizes the new PCM with the engine’s crankshaft position sensor. While our programming makes the unit plug-and-play for most functions, this final relearn procedure is often required after installation to prevent a check engine light with code P0315. It must be performed with a compatible high-level scan tool.
How do I send you my VIN?
You can add your VIN in the notes section during checkout or send us a message through the platform after you complete your purchase. We cannot ship the part until we receive your VIN to perform the programming.