Restore Peak Performance to Your Northstar V8
Is your 2004-2005 Pontiac Bonneville, Cadillac DeVille, or Seville suffering from perplexing issues like stalling, erratic shifting, or a persistent Check Engine Light? These are classic signs of a failing Powertrain Control Module (PCM), the electronic brain of your vehicle. A faulty PCM can disrupt everything from fuel delivery and ignition timing to transmission control, leaving you with an unreliable and inefficient car. This genuine, used OEM PCM, part number 12587465, is the definitive solution to restore your vehicle’s factory performance and reliability.
From the Diagnostic Bay
We had a 2005 Cadillac DeVille come in with a complaint of random stalling at stoplights and a harsh 1-2 shift. The owner had already replaced the spark plugs, ignition coils, and even the fuel pump with no success. After hooking up our diagnostic scanner, we noticed intermittent communication loss with the PCM. Instead of continuing to replace parts, we identified the root cause: the PCM itself was failing. By installing a VIN-programmed module like this one, we solved all the issues in one go, saving the customer from further frustration and unnecessary expense. Often, the component you least suspect is the one causing the most trouble.
Common Symptoms of a Failing PCM
- ✔ Persistent Check Engine Light (CEL) with various codes.
- ✔ Engine stalling, stumbling, or misfiring.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Vehicle entering ‘limp mode’ with reduced power.
- ✔ Complete no-start or intermittent starting condition.
- ✔ Failure to communicate with diagnostic scan tools.
Why Choose a VIN-Programmed Module?
Modern vehicles are complex, and the PCM is tied directly to your specific car through its Vehicle Identification Number (VIN). Simply swapping a computer from another vehicle won’t work due to anti-theft systems and specific vehicle calibrations. Our process eliminates this headache. When you purchase this 2004-2005 Bonneville PCM, we use your VIN to flash the module with the latest, most stable software updates directly from GM. This ensures that the computer is perfectly matched to your vehicle’s options and systems, making for a much smoother installation process.
Installation Guide for your 2004-2005 Bonneville PCM
Installing your replacement PCM is a straightforward process that can be done with basic hand tools. The module is located in the engine compartment on the driver’s side.
Steps:
- Disconnect the Battery: Always disconnect the negative battery terminal before working on any electronic components.
- Locate the PCM: Find the module in the LH (driver’s side) engine compartment.
- Disconnect Connectors: Carefully unplug the electrical harness connectors from the old module. There are typically release tabs that need to be depressed.
- Remove the Old PCM: Unbolt the module from its mounting bracket.
- Install the New PCM: Mount your new, pre-programmed PCM and securely reconnect the electrical harnesses.
- Reconnect Battery: Reattach the negative battery terminal.
- Security Relearn: In most cases, you will need to perform a security relearn procedure to sync the new PCM with your vehicle’s anti-theft system. This can often be done without special tools and instructions are widely available online (typically involving turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times).
This simple process gets you back on the road without a costly trip to the dealership.
Guaranteed Fitment & Compatibility
This module is a direct replacement for vehicles requiring service number 12587465. It is also a compatible replacement for service numbers 12586547 and 15576920. Please verify the part number on your original module to ensure a perfect match.
- Pontiac Bonneville: 2004-2005 (4.6L V8)
- Cadillac DeVille: 2004-2005 (ID 12587465)
- Cadillac Seville: 2004
This is a quality, tested used part sourced from a salvaged vehicle, offering an affordable and reliable alternative to a new dealership part. With our essential VIN programming service, this 2004-2005 Bonneville PCM is ready for installation right out of the box.
Frequently Asked Questions
What is a PCM and what does it do?
The Powertrain Control Module (PCM) is the main computer that controls your vehicle’s engine and transmission systems. It manages critical functions like fuel injection, ignition timing, emissions controls, and shift points to ensure optimal performance, fuel efficiency, and low emissions.
Is this part ready to install when it arrives?
Yes! This PCM is pre-programmed to your vehicle’s specific VIN before we ship it. This means it’s ready to be installed upon arrival. You will likely need to perform a simple security relearn procedure, which can be done without any special tools.
How do I provide my VIN?
After completing your purchase, please send us a message with your vehicle’s 17-digit VIN. We cannot program and ship your module without this information. You can find your VIN on your dashboard (visible through the windshield) or on your vehicle’s registration or insurance card.
Is this a new part?
No, this is a high-quality, fully tested, and functional used OEM part that has been sourced from a salvaged vehicle. This provides you with a genuine GM part at a fraction of the cost of a new one.
What if the part number doesn’t match exactly?
This module, service number 12587465, is also a direct replacement for service numbers 12586547 and 15576920. If your module has one of these numbers, this part is compatible. Always check your original part for the correct number before ordering.