Is your Cadillac STS or CTS running poorly, stalling, or showing a persistent Check Engine Light? These are common indicators of a failing Powertrain Control Module (PCM), the central computer of your vehicle. Don’t let a faulty module keep you off the road or lead to expensive, incorrect repairs. This direct-fit PCM, identified by part numbers 12600940, 12585814, and YHTZ, is the definitive solution to restore your vehicle’s performance, reliability, and efficiency. We take the guesswork and hassle out of the replacement process by programming the module specifically for your car using your VIN before it even leaves our facility. This ensures a seamless installation and immediate return to factory-spec operation.
Is Your Cadillac Showing Signs of a Failing PCM?
A failing PCM can manifest in a variety of confusing and frustrating ways. Because it controls everything from fuel injection and spark timing to transmission shifting, a single fault can create a cascade of issues. If you’re experiencing any of the following, your original module may be the culprit.
- ✔ Check Engine Light: The light is on, and you may have codes related to sensors, emissions, or processor faults.
- ✔ Engine Stalling or Misfiring: The engine may stall intermittently, run rough, or misfire, especially under load.
- ✔ No-Start Condition: The engine cranks but refuses to start, often due to a lack of spark or fuel injector signal from the PCM.
- ✔ Poor Fuel Economy: A sudden and unexplained drop in MPG can be caused by the PCM failing to manage the engine’s fuel mixture correctly.
- ✔ Harsh or Erratic Transmission Shifting: The PCM works with the transmission controller; a fault can lead to hard shifts, slipping, or being stuck in one gear.
- ✔ Failed Emissions Test: An inability to pass smog or emissions testing is frequently linked to a malfunctioning engine computer.
From the Diagnostic Bay
We had a 2006 Cadillac STS 3.6L towed in with a classic “crank, no-start” condition. The owner had already replaced the battery and the crankshaft position sensor based on some forum advice, with no luck. Our initial diagnostics showed no spark and no injector pulse. While this could point to several things, our experience with these platforms led us to check the PCM’s power and ground circuits first—they were solid. We then connected our scope and saw the PCM wasn’t commanding the ignition coils or injectors to fire, despite receiving a clear signal from the crank sensor. We swapped in one of our pre-programmed modules, performed the security relearn, and the engine fired up on the first try. It wasn’t a sensor or a wiring issue; the original computer had simply failed internally. This is a prime example of how replacing the core component—the 2005-2007 STS PCM—can be the direct and correct fix.
The Simple, Dealer-Free Solution for Your 2005-2007 STS PCM
Replacing a modern vehicle’s computer used to mean a mandatory trip to the dealership for expensive programming and calibration. Our service eliminates that step entirely. When you order from us, you get a fully prepared module that’s ready for installation right out of the box. Here’s how it works:
- Place Your Order: Add this module to your cart and complete the purchase.
- Provide Your VIN: After checkout, simply send us your vehicle’s 17-digit Vehicle Identification Number (VIN).
- We Program It: Our technicians use your VIN to access the latest, most stable GM-certified software for your exact vehicle. We flash the module, ensuring it matches your car’s specific options and systems.
- Install and Drive: Once you receive the part, you can install it. In most cases, a simple security relearn procedure (often called a CASE relearn) is all that’s needed to sync the new PCM with your car’s anti-theft system. Instructions for this are widely available and typically do not require special tools.
Guaranteed Fitment
This Electronic Control Module is a direct replacement for the following vehicles equipped with the 3.6L V6 engine and matching part numbers:
- 2005-2007 Cadillac STS (Electronic Control Module; RH engine, 3.6L)
- 2005 Cadillac CTS (Electronic Control Module; RH engine compartment, Base, ID 12585814)
Please verify that your original module carries one of the compatible part numbers (12600940, 12585814, YHTZ) to ensure a perfect match. Restore the brain of your Cadillac and get back to a smooth, reliable driving experience.
Frequently Asked Questions
Do I need to get this PCM programmed by a dealer?
No. The main benefit of our service is that we handle all the programming for you before we ship the part. We use your vehicle’s VIN to load the correct GM software and calibrations, making it ready for installation upon arrival.
What is a VIN and why is it required?
The VIN (Vehicle Identification Number) is a unique 17-digit code for your specific car. It contains information about the make, model, year, engine, and factory-installed options. Providing the VIN is essential for us to program the 2005-2007 STS PCM with the exact software your vehicle needs to function correctly.
Will I need to do anything after I install the module?
After installation, you will need to perform a security relearn procedure, also known as a CASE (Crankshaft Angle Sensor Error) relearn. This syncs the new PCM with your vehicle’s anti-theft system and crankshaft sensor. This procedure can typically be done without special scan tools and instructions are readily available online or can be provided.
How can I be sure my original PCM is the problem?
While the symptoms listed above are strong indicators, a definitive diagnosis is always recommended. This involves checking for specific diagnostic trouble codes (DTCs), verifying power and ground at the module, and ensuring sensor inputs are correct. If you are uncertain, consulting a professional technician is the best course of action.
Is this a direct replacement for part number 12585814?
Yes, this module is a fully compatible, direct replacement for original units with part numbers 12600940, 12585814, or service number YHTZ. It meets or exceeds all original equipment specifications.