Restore Peak Performance to Your GM Truck or SUV
Is your HUMMER H2, Silverado, or Sierra suddenly stalling, shifting erratically, or refusing to start? As a mechanic with over two decades of experience under the hood, I’ve seen these symptoms countless times. Often, the culprit isn’t a faulty sensor or a bad wire; it’s the brain of the operation—the Powertrain Control Module (PCM). This isn’t just a replacement part; it’s a definitive solution to get your vehicle running reliably again. We take a high-quality replacement PCM, part number 12582605, and flash it with the very latest official GM software calibrated specifically to your vehicle’s VIN. This eliminates the guesswork and the expensive trip to the dealership for programming.
From the Diagnostic Bay: The Ghost in the Machine
I remember a 2005 Silverado 2500HD that came into my shop with a problem that was driving the owner crazy. It had intermittent hard shifting and a random no-start condition that never threw a consistent code. He’d already replaced the throttle body and a few sensors. After hooking up my scan tool and monitoring live data, I noticed the PCM was dropping communication intermittently—a classic sign of an internal failure. These P59 controllers, located under the battery on most of these trucks, are prone to failure from years of heat cycles and vibration. We installed a VIN-programmed PCM just like this one, performed the security relearn, and the truck ran perfectly. It’s a common story for this otherwise bulletproof GM platform, and a reliable PCM is the key to fixing it right the first time.
Common Signs of a Failing GM PCM
If the central computer of your vehicle is failing, it can cause a wide range of confusing issues. Before you start replacing expensive sensors, check if your truck is showing these classic symptoms of a bad PCM. A failing 2003-2007 HUMMER H2 PCM can manifest in several ways:
- ✔ Check Engine Light is on with communication-related Diagnostic Trouble Codes (DTCs) like U0100, or internal fault codes like P0601, P0602, or P0606.
- ✔ The engine cranks but refuses to start for no apparent reason.
- ✔ Unexplained stalling, either while driving or at an idle.
- ✔ Rough or unstable engine idle.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ The vehicle enters a reduced power or “limp mode.”
Your Step-by-Step Installation Roadmap
Installing your pre-programmed PCM is a straightforward job for a DIYer with basic tools. The most critical part is providing us with your correct VIN upon purchase. We handle the complex programming; you handle the simple installation.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 15 minutes for the system capacitors to discharge.
- Locate the PCM: On most compatible trucks and SUVs like the Hummer H2, Silverado, and Tahoe, the PCM is located in the engine bay on the driver’s side, typically under the battery tray or near the airbox.
- Disconnect the Harnesses: Carefully release the locking tabs on the electrical connectors and pull them straight out from the module. There are typically two or three large connectors. Do not force them.
- Remove the Old Module: Unbolt the PCM from its mounting bracket. Keep the hardware as you will need it to install the new unit.
- Install the New PCM: Mount your new, pre-programmed PCM and securely reconnect the electrical harnesses. Ensure the locking tabs click into place.
- Reconnect the Battery: Re-attach the negative battery terminal.
- Perform Security Relearn: You MUST perform a security relearn procedure (also known as a Passlock or VATS relearn). This simple procedure pairs the new PCM to your vehicle’s anti-theft system. It typically involves turning the key to the ‘ON’ position for 10-12 minutes, then ‘OFF’, and repeating this cycle three times. Your vehicle will not start until this is completed.
Will This Fit My Truck or SUV?
This PCM is a direct-fit replacement for a wide variety of General Motors vehicles. Please verify your vehicle is on the list below and that your original module carries one of the compatible service numbers: 89017750, 12582605, 12589463, 12602802, 89017734, or 28042802. This is the correct 2003-2007 HUMMER H2 PCM and also fits the following:
CHEVROLET SILVERADO 1500, 2500, 3500 (2003-2007 Classic)
CHEVROLET SSR (2003)
CHEVROLET SUBURBAN 1500, 2500 (2003-2006)
CHEVROLET TAHOE (2003-2006)
CHEVROLET TRAILBLAZER EXT (2003)
CADILLAC ESCALADE, ESV, EXT (2003-2006)
GMC ENVOY XL (2003)
GMC SIERRA 1500, 2500, 3500 (2003-2007 Classic)
GMC SIERRA DENALI (2003-2007 Classic)
GMC YUKON & YUKON XL 1500, 2500 (2003-2006)
HUMMER H2 (2003-2007)
ISUZU ASCENDER (2003)
Note: Please check the specific options in the original fitment data if your vehicle is a 2004 or 2007 model to ensure perfect compatibility.
Frequently Asked Questions
Frequently Asked Questions
How do I provide my VIN number?
After you complete your purchase, simply send us a message with your 17-digit Vehicle Identification Number (VIN). We cannot program and ship your module without it.
Is this part difficult to install myself?
Not at all. The physical replacement is simple, requiring only basic hand tools. Since we program the module for you, the only remaining step is a security relearn procedure that you can do yourself in about 30 minutes with just your car key.
What is a security relearn and why is it necessary?
The security relearn (VATS/Passlock) syncs the new PCM to your vehicle’s anti-theft system. Without it, the vehicle will not start. It’s a simple, key-on/key-off procedure that doesn’t require any special tools.
Will this fix my check engine light?
If the check engine light is caused by an internal PCM failure (like codes P0601-P0606) or a communication fault, this module will resolve the issue. However, if the light is on due to a bad sensor or other system fault, that separate issue will still need to be addressed.
Is this a brand new part?
This is a high-quality, tested replacement part that has been fully inspected and programmed with the latest GM software. It is guaranteed to restore your vehicle’s functionality and performance.
Does this PCM support my 2003-2007 HUMMER H2 PCM functions?
Yes, when programmed with your VIN, this module will operate exactly as the original unit did, controlling all engine and transmission functions precisely for your specific vehicle configuration.