Is Your Buick Rainier or Trailblazer Running Rough?
If you’re dealing with frustrating issues like a persistent check engine light, erratic engine behavior, harsh shifting, or even a no-start condition, a failing Powertrain Control Module (PCM) is a likely culprit. The PCM is the brain of your vehicle, managing everything from fuel injection and ignition timing to transmission operation. When it starts to fail, it can cause a cascade of problems that are often misdiagnosed, leading to wasted time and money on unnecessary parts. This replacement PCM, part number 12573576, is the definitive solution to restore your vehicle’s performance and reliability.
The Plug-and-Play Solution: Pre-Programmed for Your Vehicle
Forget expensive dealership visits and the hassle of finding a shop to program a new module. We handle the critical programming for you before we ship. Simply provide us with your vehicle’s 17-digit Vehicle Identification Number (VIN) during checkout, and our technicians will flash the unit with the latest GM-certified software specific to your 2004-2005 Rainier, Envoy, Trailblazer, or other compatible model. This ensures that all parameters for your engine, transmission, and security system are perfectly matched, making installation straightforward.
From the Diagnostic Bay
We had a 2005 GMC Envoy with the 4.2L engine come in with a random P0300 misfire code and a complaint of stalling at red lights. The owner had already replaced all six spark plugs and ignition coils, the mass airflow sensor, and even the throttle body, with no success. The symptoms were intermittent, making it a real headache. After hooking up our diagnostic scanner and monitoring live data, we noticed the fuel trim and ignition timing commands from the PCM were fluctuating wildly for no reason. We swapped in a VIN-programmed PCM, and the engine immediately smoothed out. The fuel trims stabilized, and the stalling issue was gone for good. It’s a classic case where the core problem was the computer itself, not the parts it was controlling.
Symptoms of a Failing 2004-2005 Rainier PCM
- ✔ Persistent Check Engine Light (CEL) with communication or processor-related codes.
- ✔ Unexplained engine stalling or stumbling, especially when warm.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh, erratic, or delayed transmission shifting.
- ✔ Engine misfires even after replacing plugs and coils.
- ✔ The vehicle cranks but refuses to start.
- ✔ Failure to pass an emissions test due to module-related faults.
Guaranteed Compatibility and Simple Installation
This module is a direct replacement for a wide range of GM SUVs equipped with the 4.2L inline-6 engine. It is compatible with multiple original equipment part numbers, ensuring a perfect match. Installation is typically simple for a DIY mechanic: disconnect the negative battery terminal, locate the PCM in the engine bay (usually on the driver’s side), carefully unplug the wiring harnesses, unbolt the old unit, and install the new one in its place. After reconnecting the battery, you may need to perform a simple security relearn procedure, which takes about 30 minutes and requires only your ignition key.
This module is a direct fit for the following part numbers:
12573576, 12574976, 12577955, 12584593, 16255757, 19210065
Fits a Wide Range of GM Models Including:
- 2004-2005 Buick Rainier 4.2L
- 2003-2005 GMC Envoy, Envoy XL, Envoy XUV 4.2L
- 2003-2005 Chevrolet Trailblazer & Trailblazer EXT
- 2003-2004 Oldsmobile Bravada
- 2003-2005 Isuzu Ascender 4.2L
- 2005-2006 Saab 9-7X 4.2L
Frequently Asked Questions
Do I need to get this computer programmed?
No. This is the biggest benefit of our service. We program the PCM with the latest GM software using the VIN you provide before shipping. It arrives ready for installation.
What is a security relearn procedure?
This is a simple process that syncs the new PCM with your vehicle’s anti-theft system (Passlock/VATS). It typically involves cycling the ignition key on and off in a specific sequence for about 30 minutes. Instructions are readily available online, and no special tools are required.
Where is the PCM located on my 2004 Buick Rainier?
On the Buick Rainier and similar platforms like the Trailblazer and Envoy, the PCM is located in the engine compartment, typically on the driver’s side, near the firewall or inner fender.
Will this fix my check engine light?
If the check engine light is caused by an internal failure of the PCM, then yes, this part will resolve the issue. However, it’s essential to properly diagnose your vehicle’s trouble codes first to ensure you are not replacing a good PCM for a bad sensor or wiring problem.
What information do you need from me after I order?
We only need your complete 17-digit Vehicle Identification Number (VIN). You can usually find this on your driver’s side door jamb sticker, your insurance card, or at the base of the windshield on the driver’s side.