2004 CTS Powertrain Control Module 12578127 | Programmed to Your VIN

Restore Peak Performance to Your GM Vehicle

If you’re dealing with the frustration of a check engine light that won’t go away, poor engine performance, or even a no-start condition, a failing Powertrain Control Module (PCM) is often the culprit. As the central computer of your vehicle, the PCM controls everything from fuel mixture and ignition timing to transmission shifting. When it fails, it can cause a cascade of problems that are difficult to diagnose. This replacement module is your direct-fit, reliable solution, designed to get your vehicle running smoothly again without a costly trip to the dealership.

This isn’t just a part; it’s a plug-and-play fix. We take the hassle out of the repair by programming the module specifically for your vehicle using your VIN. This ensures all factory settings and the latest GM software updates are loaded before it even ships. You receive a component that’s ready for installation, saving you time and the expense of specialized programming tools.

Is Your Vehicle Exhibiting These Issues?

A failing PCM can manifest in many ways. If you’re noticing any of the following, it might be time for a replacement:

• ✔ Check Engine Light is on with codes like P0601, P0606, or other internal processor faults.
• ✔ Engine cranks but will not start.
• ✔ Rough idling, stalling, or hesitation during acceleration.
• ✔ Noticeable decrease in fuel economy.
• ✔ Harsh or erratic transmission shifting.
• ✔ Communication errors with scan tools (U-codes).
• ✔ Failure to pass an emissions inspection.

Your Straightforward Installation Guide

Installing your new 2004 CTS Powertrain Control Module is a manageable task for a confident DIYer. While the exact location varies by model (see fitment list), the general process is similar.

1. Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post.
2. Locate the PCM: On the 2004 Cadillac CTS, it’s typically found in the engine compartment on the passenger’s side (RH). For trucks and vans, it’s often under the battery tray on the driver’s side (LH).
3. Disconnect and Remove: Carefully unplug the electrical connectors. There are usually locking tabs that need to be released. Once disconnected, unbolt the module from its mounting bracket and remove it.
4. Install the New Module: Bolt the new, pre-programmed module into place. Reconnect the electrical connectors, ensuring they click securely into place.
5. Reconnect Power: Reattach the negative battery terminal.
6. Perform Security Relearn: This is a critical final step. Most GM vehicles require a security relearn procedure to sync the new PCM with your vehicle’s anti-theft system. This can typically be done without special tools and involves a sequence of turning the key on and off. A quick search for your specific model’s “VATS relearn procedure” will provide the exact steps.

Verified Compatibility for Your Vehicle

This module, part number 12578127, is a direct replacement for a wide range of GM vehicles. It is compatible with service numbers 12581565, 12570557, 12570558, 12576106, 12576869, 88864822, 89017733 and more. Please verify your vehicle is on the list below:

• Cadillac CTS (2004) – Electronic Control Module; (RH engine compartment), Base, ID 12581565
• Chevrolet Corvette (2004) – Electronic Control Module; (RH engine compartment), ID 12581565
• Chevrolet Avalanche 2500 (2003) – Electronic Control Module; (LH front under battery)
• Chevrolet Blazer S10 (2003) – Electronic Control Module; (RH front engine compartment)
• Chevrolet Express Vans (1500, 2500, 3500) (2003) – Electronic Control Module; (LH rear engine compartment)
• Chevrolet S10 Pickup (2003) – Electronic Control Module; (RH front engine compartment), 4.3L
• Chevrolet Silverado Pickups (1500, 2500, 3500) (2003) – Powertrain/Engine Control Module; (LH front under battery), various engines
• Chevrolet Suburban 2500 (2003) – Electronic Control Module; (LH front under battery), 8.1L
• GMC Jimmy S15 (2003) – Electronic Control Module; (RH front engine compartment)
• GMC Safari / Chevrolet Astro (2003) – Electronic Control Module; (LH front by battery)
• GMC Savana Vans (1500, 2500, 3500) (2003) – Engine Computer; (LH rear engine compartment)
• GMC Sierra Pickups (1500, 2500, 3500) (2003) – Powertrain/Electronic Control Module; (LH front under battery), various engines
• GMC Sonoma (2003) – Electronic Control Module; (RH front engine compartment), 4.3L
• GMC Yukon XL 2500 (2003) – Electronic Control Module; (LH front under battery), 8.1L

By ordering this 2004 CTS Powertrain Control Module, you are choosing a reliable, tested component that restores the vital link between your engine, transmission, and electronics. Place your order, provide your VIN, and let us handle the programming for you.