Bring Your GM Truck or SUV Back to Life
Is your ride suffering from a frustrating no-start condition, erratic shifting, or a persistent check engine light that just won’t go away? These are classic signs of a failing Powertrain Control Module (PCM), the electronic brain of your vehicle. Don’t let confusing diagnostics and the threat of a massive dealership bill sideline you. This VIN-programmed engine computer, service number 12586242, is the definitive, straightforward solution to restore your vehicle’s performance and your peace of mind. Get back to confident, worry-free driving with a part that’s ready to install right out of the box.
Warning Signs and How to Overcome Them
A faulty PCM can manifest in numerous ways. If you’re experiencing any of the following, this module is the likely solution:
- ✔ Unexplained stalling or rough idling.
- ✔ Drastic decrease in fuel economy.
- ✔ Harsh or delayed automatic transmission shifts.
- ✔ Failure to pass an emissions test.
- ✔ Diagnostic Trouble Codes (DTCs) related to module communication, sensor circuits, or processor failure (e.g., P0601, P0606, U0100).
- ✔ Complete no-start condition where the engine cranks but won’t fire.
Installing this pre-programmed module resolves these core issues, restoring factory-spec engine performance, smooth shifting, and optimal fuel efficiency.
An Expert’s Note on Ground Connections
Before you replace any computer, take 15 minutes to check your vehicle’s main ground connections. On these GM platforms, a corroded or loose ground strap (especially the one from the engine block to the chassis) can mimic PCM failure. It’s a simple check that has saved me countless hours and my customers thousands of dollars over the years. A clean, tight ground is the foundation of a healthy electrical system.
Guided Installation to Restore Peak Performance
We’ve made this repair as simple as possible. Because we program the module to your vehicle’s specific VIN before shipping, you can bypass the expensive trip to the dealer. Follow these steps for a successful installation:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 10 minutes to allow the system to fully discharge.
- Locate the Old Module: On most compatible vehicles, the PCM is found in one of two places: either in the engine bay next to the air filter box (common on Trailblazer, Envoy, Rainier) or under the battery tray on the driver’s side frame rail (common on Silverado, Sierra, Suburban).
- Swap the Computers: Carefully unplug the electrical connectors from the old PCM. They have locking tabs that need to be released. Once disconnected, unbolt the old module from its bracket and set it aside. Secure the new module in its place and firmly reconnect all electrical harnesses.
- Reconnect Power: Re-attach the negative battery terminal and ensure it’s tight.
- Perform Security Relearn: This is a critical final step. Turn the key to the ‘ON’ position (without starting the engine) for 10-12 minutes. The ‘Security’ light on the dash should turn off or stop flashing. Turn the key off for 10 seconds, then repeat this cycle two more times for a total of three cycles and about 30 minutes. After the third cycle, the vehicle will be synched to the new PCM and should start right up.
Tailored Fit for Your GM Vehicle
This 2004 Envoy PCM is a direct-fit replacement for a wide range of GM trucks and SUVs. It is compatible with modules bearing service numbers 12586242, 19299226, 89017738, and broadcast codes such as YFKD, YFKF, YFKH, YFKJ, YFKX, YFXL, YFXM, YFXN, YFXP, and YHTN. Please verify your service number or contact us with your VIN to confirm perfect compatibility for models including:
- Buick Rainier (2004) – 5.3L
- Cadillac Escalade, ESV, EXT (2004)
- Chevrolet Avalanche 1500 (2004)
- Chevrolet Silverado & Sierra 1500, 2500, 3500 (2004) – Gasoline Engines
- Chevrolet SSR (2004)
- Chevrolet Suburban & Yukon XL 1500, 2500 (2004)
- Chevrolet Tahoe & GMC Yukon (2004)
- Chevrolet Trailblazer EXT (2004) – 5.3L
- GMC Envoy XL & XUV (2004) – 5.3L
- Hummer H2 (2004)
- Isuzu Ascender (2004) – 5.3L
Frequently Asked Questions
Do I need to get this computer programmed by a dealer?
Absolutely not! That’s the primary benefit of our service. You provide us with your vehicle’s VIN during checkout, and we flash the module with the latest GM-certified software for your specific vehicle. It arrives ready for installation.
What is the ‘Security Relearn Procedure’ and is it difficult?
It’s a simple process that syncs the new PCM to your vehicle’s anti-theft system. It involves cycling the ignition key and waiting, as described in the installation steps above. It requires no special tools and is essential for the vehicle to start after the new module is installed.
Where is the PCM located on my 2004 Sierra or Silverado?
For most full-size trucks and SUVs like the Silverado, Sierra, Tahoe, and Suburban, the PCM is located on the driver’s side, mounted to the frame rail underneath the battery tray.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM controls both engine and transmission functions. If the shifting issues are caused by faulty electronic signals or a failing processor within the module, this replacement will solve the problem. However, it will not fix internal mechanical failures within the transmission itself.
What information do you need from me?
All we need is your 17-digit Vehicle Identification Number (VIN). You can typically find this on your driver’s side dashboard (visible through the windshield), on your door jamb sticker, or on your vehicle’s registration and insurance documents.