Is Your Saturn Relay Running Rough? The PCM Might Be the Culprit.
The Powertrain Control Module, or PCM, is the central computer of your 2005-2006 Saturn Relay. It manages everything from fuel injection and ignition timing to transmission shifting and emissions control. When it starts to fail, it can cause a cascade of confusing and frustrating problems, often leaving you stranded. If you’re dealing with an intermittent no-start, a persistent check engine light, or erratic engine behavior, a faulty PCM is a likely cause. This replacement module is the key to restoring your vehicle’s reliability and performance.
From the Diagnostic Bay
We had a 2005 Chevy Uplander (which uses this same PCM) come into the shop with a complaint of intermittent stalling at stoplights. The owner had already replaced the battery and alternator, but the problem persisted. No hard codes were stored, just a few communication loss codes in other modules. After checking all the grounds and power feeds to the PCM, we connected a scope and saw the 5-volt reference signal dropping out randomly. This is a classic internal PCM failure. We sourced a quality used module, programmed it to the van’s VIN, and the stalling issue was completely resolved. It’s a reminder that sometimes the most baffling electronic gremlins lead straight back to the brain of the operation.
Symptoms of a Failing 2005-2006 Saturn Relay PCM
A failing engine computer can manifest in numerous ways. If you’re experiencing any of the following, it’s time to consider a replacement:
- ✔ Persistent Check Engine Light (CEL) with communication-related codes (e.g., U-codes).
- ✔ Engine misfires, stumbling, or poor acceleration.
- ✔ Drastic decrease in fuel economy for no apparent reason.
- ✔ Vehicle refuses to start, or starts and immediately stalls.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Seeming failure of multiple sensors at once.
Guaranteed Compatibility and Simple Installation
This is a genuine, used OEM Powertrain Control Module that has been carefully inspected and is ready for service. We take the guesswork out of the replacement process. By providing us with your vehicle’s VIN at checkout, we will program the module with the latest GM-certified software specific to your vehicle. This ensures all factory settings are correct and that the module will communicate properly with the other computers in your van. This unit is a direct replacement for part numbers 12591856 and 12591279.
This module is compatible with a range of GM vehicles. Please verify fitment for your specific model and engine:
- 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; Sdn, LH front engine compartment)
- 2005 Chevrolet Uplander (Electronic Control Module; LH engine compartment)
Frequently Asked Questions
Do I need to do any programming myself?
No. We handle all the programming before the module is shipped. Simply provide your vehicle’s VIN during or after checkout, and we will flash the unit with the correct software for your specific vehicle. It will arrive ready to install.
What is a VIN and where do I find it?
The VIN is your Vehicle Identification Number, a unique 17-digit code. You can typically find it on a plate on the driver’s side dashboard (visible through the windshield), on the driver’s side door jamb sticker, or on your vehicle’s registration and insurance documents.
Is any additional setup required after installation?
In most cases, this module is plug-and-play after our programming. However, some vehicles may require a security relearn procedure (also known as a CASE relearn or anti-theft relearn). This is a simple procedure that can often be done without special tools and typically involves a sequence of key turns. Instructions can be readily found online for your specific model.
Is this a new part?
No, this is a high-quality, tested, and functional used part sourced from a salvaged vehicle. This provides an affordable and reliable alternative to expensive new modules.
How do I know this will fix my car’s problem?
While this part resolves the issues listed in the description, we always recommend a proper diagnosis by a qualified mechanic. This ensures you are replacing the correct part and avoids unnecessary expenses. A faulty PCM can mimic other issues like a bad sensor or wiring problem.