Is Your GM Vehicle Running Rough or Not Starting?
If you’re experiencing frustrating issues like a persistent Check Engine Light, poor fuel economy, erratic shifting, or a no-start condition in your Saturn Relay, Chevy Equinox, or other compatible GM vehicle, the root cause is often a failing Powertrain Control Module (PCM). As the central computer, the PCM is the brain behind your engine’s performance and efficiency. When it begins to fail, it can create a cascade of problems that are difficult to diagnose. Don’t let a faulty computer keep you off the road. This genuine, used OEM PCM, part number 12591279, is the reliable and cost-effective solution you need.
Why a Pre-Programmed PCM is Your Best Choice
Replacing a PCM isn’t as simple as swapping out a battery. The module must be correctly programmed with your vehicle’s specific Vehicle Identification Number (VIN) and the latest GM software updates to function correctly. Without proper programming, the vehicle won’t start, or it will run poorly and display error messages. We take the guesswork and hassle out of the process. Simply provide us with your VIN after purchase, and our technicians will professionally flash this module for you. It will arrive at your door, ready for installation and a simple key relearn procedure you can do yourself.
From the Diagnostic Bay
We had a 2005 Chevy Uplander come into the shop that had its owner completely stumped. The van would randomly stall at stoplights and sometimes refuse to shift out of second gear. The owner had already replaced the alternator and a couple of sensors with no luck. After connecting our scanner, we saw communication error codes with the transmission module and erratic data from the throttle position sensor, even though the sensor itself was new. This pointed us towards the central command unit. We swapped in a known-good, programmed PCM, and the van immediately ran like new. The original PCM had internal circuit failure, causing it to send corrupt data across the vehicle’s network. This is a classic case where only replacing the brain can fix the body’s problems.
Common Symptoms of a Failing PCM
- ✔ Persistent Check Engine Light (CEL) with codes like P0601, P0606, or communication errors.
- ✔ Vehicle refuses to start or has difficulty starting.
- ✔ Poor engine performance, including misfires, rough idling, and stalling.
- ✔ A significant drop in fuel efficiency.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Failure to pass emissions testing.
- ✔ Other modules in the vehicle (like the BCM or TCM) reporting a loss of communication with the PCM.
The Right Part for Your 2005 Saturn Relay PCM Replacement
This unit, part number 12591279 (also interchangeable with 12591856), is a tested, used OEM component sourced from a salvaged vehicle. This ensures you get a factory-quality part without the new-part price tag. Our service restores it to plug-and-play condition for your specific vehicle. By providing your VIN, you guarantee that the software loaded onto the computer perfectly matches your vehicle’s original configuration, including engine, transmission, and emissions options.
Installation is Straightforward
While professional installation is always an option, many DIY mechanics can perform this replacement. The module is typically located in the LH (driver’s side) engine compartment.
- Disconnect the Battery: Always disconnect the negative battery terminal before working on any electronic components.
- Locate and Remove the Old PCM: Unplug the wiring harness connectors and unbolt the module from its bracket.
- Install the New PCM: Bolt the new module in place and securely reconnect the wiring harnesses.
- Reconnect the Battery: Reattach the negative battery terminal.
- Perform Key Relearn Procedure: You will need to perform a security relearn procedure to sync your vehicle’s keys with the new computer. This procedure typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times. Specific instructions for your vehicle are widely available online.
Guaranteed Fitment for Your Vehicle
This Electronic Control Module is a direct replacement for the following vehicles. Please ensure your vehicle and options match the list below:
- 2005 Chevrolet Equinox (Electronic Control Module; LH engine compartment)
- 2005 Saturn RELAY (Electronic Control Module; LH engine compartment)
- 2006 Saturn RELAY (Electronic Control Module; LH engine compartment, 3.5L)
- 2005 Chevrolet Malibu (Electronic Control Module; LH dash, VIN Z 4th digit New Style, 3.5L)
- 2005 Pontiac Montana (Electronic Control Module; LH engine compartment, SV6)
- 2005 Buick Terraza (Electronic Control Module; LH engine compartment)
- 2005 Pontiac G6 (Electronic Control Module; Sedan, LH front engine compartment)
- 2005 Chevrolet Uplander (Electronic Control Module; LH engine compartment)
Frequently Asked Questions
Do I need to do anything after installing this PCM?
Yes. Although we program the module with your vehicle’s VIN and software, you will need to perform a security relearn procedure (also known as a key relearn). This allows your vehicle’s anti-theft system to recognize the new PCM. This procedure can typically be done by you at home in about 30 minutes and does not require a special scan tool.
How do I provide my VIN number?
After you complete your purchase, you will receive instructions on how to send us your vehicle’s 17-digit VIN. You can typically reply to your order confirmation email or send it through the platform’s messaging system. We cannot program and ship your part without it.
Is this a new part?
No, this is a genuine, used OEM part that has been sourced from a salvaged vehicle. We inspect and test each unit to ensure it is fully functional before programming and shipping it to you.
Will this fix my vehicle’s problem for sure?
This PCM will correct any issues directly caused by a faulty PCM. However, it is crucial to ensure your vehicle has been properly diagnosed. This part will not fix problems caused by other faulty components, such as bad sensors, wiring issues, or mechanical failures.
What if I order the wrong part?
Please verify that your vehicle is on the compatibility list and that your current module’s part number is 12591279 or 12591856. Because this part is programmed specifically for your vehicle’s VIN, it is critical to confirm fitment before ordering. Contact us if you are unsure, and we can help you verify.