Restore Peak Performance to Your Cadillac or Pontiac
Is your 2004-2005 Cadillac DeVille, Seville, or Pontiac Bonneville suffering from perplexing issues like a persistent check engine light, poor fuel economy, erratic shifting, or even a no-start condition? The problem often lies not with the engine or transmission itself, but with its brain: the Powertrain Control Module (PCM). This vital component is responsible for managing countless parameters to keep your 4.6L Northstar V8 running at its best. When it fails, the symptoms can be frustrating and difficult to diagnose. This listing offers a direct, reliable solution: a genuine, used OEM PCM, part number 12586547, pre-programmed specifically for your vehicle.
We had a 2005 DeVille come into the shop with a complaint of harsh, unpredictable transmission shifts and a general lack of power. The owner had already spent a small fortune at a transmission shop, who couldn’t find anything mechanically wrong. After hooking up our diagnostic scanner, we noticed intermittent communication loss with the PCM. Instead of a costly transmission rebuild, the solution was a replacement PCM. Once we installed a properly programmed module, the car drove like it just left the showroom. It’s a classic case where the ‘brain’ was the issue, not the ‘body’, saving the customer thousands.
Why a Pre-Programmed 2004-2005 DeVille PCM is Your Best Solution
Replacing an engine computer isn’t as simple as swapping out a battery. The PCM is programmed with your vehicle’s specific Vehicle Identification Number (VIN) and contains crucial software for the engine, transmission, and anti-theft system (Passlock/VATS). Our service eliminates the guesswork and costly dealership visits. We take a genuine, tested OEM module and flash it with the latest official GM software updates using your vehicle’s VIN. This ensures that the module you receive is 100% compatible with your car’s specific configuration and options. You get a part that is ready for installation right out of the box, saving you from towing fees and expensive dealer programming labor.
Common Symptoms of a Failing PCM
- ✔ Persistent Check Engine Light (CEL) that won’t go away.
- ✔ Unexplained drop in fuel mileage.
- ✔ Engine stalling, sputtering, or running rough.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Intermittent no-start or hard-starting conditions.
- ✔ Communication error codes (U-codes) on a diagnostic scan.
- ✔ Failure to pass state emissions testing.
Simple Installation Process
This module is located in the engine compartment on the driver’s side. Installation is straightforward for a DIY mechanic or any professional technician. After physically swapping the module, you will need to perform a simple security relearn procedure. This procedure syncs the new PCM with your vehicle’s anti-theft system and keys. It does not require any special tools and typically takes about 30 minutes to complete. Instructions for this process are widely available online and are simple to follow.
Vehicle and Part Compatibility
This module is a direct replacement for vehicles requiring service numbers 12587465, 12586547, or 15576920. Please verify the part number on your original module to ensure a perfect match.
This part will fit the following vehicles with these options:
- 2004-2005 Pontiac Bonneville: Electronic Control Module; (LH engine compartment), 4.6L
- 2005 Cadillac DeVille: Electronic Control Module; (LH engine compartment), ID 12587465
- 2004 Cadillac DeVille: Electronic Control Module; (LH engine compartment)
- 2004 Cadillac Seville: Electronic Control Module; (LH engine compartment)
IMPORTANT: After your purchase, you must provide us with your vehicle’s VIN. We cannot ship your order until we have this information to program the module correctly.
Frequently Asked Questions
Why do you need my VIN?
Your Vehicle Identification Number (VIN) is essential for programming the PCM. It allows us to load the exact GM-certified software calibration that matches your car’s specific engine, transmission, and factory options, ensuring perfect compatibility and performance.
Is this a plug-and-play part?
Almost. The module is programmed to be plug-and-play regarding engine and transmission functions. However, you MUST perform a security relearn procedure after installation to sync the module with your car’s anti-theft system. This is a simple procedure that you can do yourself in about 30 minutes without any special tools.
Will I need to take my car to a dealer after installation?
No. Our VIN programming service eliminates the need for a trip to the dealership. Once you complete the security relearn procedure, your vehicle will be ready to drive.
What is the security relearn procedure?
It’s a sequence of key turns designed to teach the vehicle to recognize the new PCM. A typical GM procedure involves turning the key to the ‘ON’ position for 10 minutes, then ‘OFF’ for 10 seconds, and repeating this cycle three times. Your vehicle’s specific instructions can be easily found in your owner’s manual or online.
Is this a new or used part?
This is a high-quality, genuine OEM part sourced from a salvaged vehicle. Each unit is thoroughly inspected and tested before being programmed and shipped to ensure it meets our high standards of reliability and performance.