Restore Peak Performance to Your Cadillac or Pontiac
Is your 2004-2005 Cadillac DeVille, Seville, or Pontiac Bonneville suffering from baffling engine issues? Stalling, poor fuel economy, a persistent check engine light, or a no-start condition can often be traced back to a failing Powertrain Control Module (PCM), the central computer of your vehicle. This isn’t just a replacement part; it’s a complete, plug-and-play solution. We are offering a genuine, used GM PCM (Service No. 12587465) that will be professionally programmed with the latest GM software updates specifically for your vehicle’s Vehicle Identification Number (VIN). This critical programming step ensures that the computer communicates perfectly with your engine, transmission, and all other onboard systems, restoring the smooth operation and reliability you expect.
Common Symptoms of a Failing PCM
A faulty engine computer can manifest in numerous ways, often mimicking other component failures. If you’ve checked the basics and are still stumped, your PCM might be the culprit. Here are common indicators that your module needs replacement:
- ✔ Persistent Check Engine Light: Especially with communication-related trouble codes (U-codes) or codes that point to internal processor errors.
- ✔ Engine Performance Problems: Unexplained stalling, rough idling, hesitation during acceleration, misfires, or a sudden drop in fuel efficiency.
- ✔ Intermittent or No-Start Condition: The engine cranks but refuses to start, or starts unreliably. This can happen when the PCM fails to command the fuel pump or ignition system.
- ✔ Erratic Transmission Shifting: The PCM plays a key role in controlling shift points. Harsh shifting, getting stuck in gear, or delayed engagement can be a sign of a bad computer.
- ✔ Communication Failures: If your diagnostic scan tool cannot communicate with the engine computer, it’s a strong sign the module itself has failed.
The Direct Solution: A VIN-Programmed 2004-2005 DeVille PCM
Don’t settle for a generic, unprogrammed module that will require expensive dealer intervention. Our process is designed to get you back on the road quickly and affordably. We take a thoroughly tested, functional OEM computer and flash it with your vehicle’s specific calibration files using your VIN. This ensures all factory settings, including those for your engine, transmission, and emissions equipment, are perfectly matched. This module is a direct replacement for service numbers 12587465, 12586547, and 15576920, providing broad compatibility for the vehicles listed below.
From the Diagnostic Bay
We once had a 2004 Cadillac Seville in the shop with a ghost of a problem. The owner had replaced plugs, coils, and even injectors chasing a random misfire on cylinder 3 that only happened under heavy load. Scopes and scanners showed nothing obvious. After hours of tracing wires, we decided to monitor the injector driver command directly from the PCM. We discovered the driver for cylinder 3 was intermittently dropping out. We installed one of our VIN-programmed PCMs, performed the quick security relearn, and the car ran perfectly. It’s a reminder that sometimes the most elusive problems lead right back to the vehicle’s brain.
Installation and Setup
This PCM is located in the engine compartment on the driver’s side (LH side). Installation is straightforward for anyone with basic mechanical skills:
- Disconnect the Battery: Always disconnect the negative battery terminal before working on any electronic components.
- Access the PCM: Locate the module in the engine bay.
- Unplug and Unbolt: Carefully release the locking tabs on the electrical connectors and pull them straight out. Then, remove the bolts holding the module in place.
- Install the New PCM: Bolt the new, programmed PCM into place and securely reconnect the electrical harnesses.
- Reconnect the Battery: Reattach the negative battery terminal.
- Perform Security Relearn: You will need to perform a simple anti-theft relearn procedure to sync the new computer with your car’s keys. This typically involves a 30-minute process of cycling the key in the ignition. Instructions are readily available online or we can point you to them.
Guaranteed Fitment
This electronic control module is a confirmed fit for the following vehicles and options:
- Pontiac Bonneville: 2004-2005 (with 4.6L engine)
- Cadillac DeVille: 2004
- Cadillac DeVille: 2005 (with module ID 12587465)
- Cadillac Seville: 2004
After placing your order, please provide your VIN to ensure we can program the module correctly before shipment. This step is mandatory and guarantees a successful repair.
Frequently Asked Questions
Do I need to do any additional programming?
No. We handle all the necessary programming to your vehicle’s VIN before we ship the part. The only step you may need to perform after installation is a simple security relearn procedure, which syncs the new computer to your existing keys and takes about 30 minutes.
How do I provide my VIN number?
Simply add your 17-digit VIN in the order notes during checkout, or reply to your order confirmation email with the information. We cannot ship your part until we receive your VIN.
Is this a new part?
This is a high-quality, used OEM General Motors part sourced from a salvaged vehicle. Each unit is inspected and tested to ensure full functionality before being programmed and shipped. This provides OEM reliability without the high dealer cost.
What is the security relearn procedure?
It’s a process required by GM’s anti-theft system to authorize a new computer. For most of these vehicles, it involves turning the key to the ‘ON’ position for 10 minutes, off for 10 seconds, and repeating this cycle three times. It’s a simple procedure that requires no special tools.
Will this fix my specific problem?
This part is a direct solution for a failed PCM. While the symptoms listed are very common for PCM failure, we always recommend a proper diagnosis by a qualified mechanic to confirm the PCM is the root cause of your issues before ordering.