Restore Peak Performance to Your GM Truck or SUV
Is your 2003 Isuzu Ascender or GM truck running rough, refusing to start, or showing a persistent Check Engine Light? The Powertrain Control Module (PCM) is the brain of your vehicle’s engine and transmission, and when it fails, it can cause a wide range of frustrating and confusing problems. From poor fuel mileage to erratic shifting, a faulty PCM can make your reliable vehicle feel unpredictable. This replacement PCM, part number 12582605, is the definitive solution to restore your vehicle’s original performance and reliability.
We take the guesswork and high costs out of the repair. Unlike a generic module from a parts store, this PCM arrives at your door pre-programmed with the latest GM factory software updates, specifically matched to your vehicle’s VIN. This means you can skip the expensive trip to the dealership for programming. It’s a direct-fit, ready-to-install solution designed to get you back on the road quickly and confidently.
From the Diagnostic Bay
I remember a 2005 Silverado 1500 that was towed into my shop. The complaint was simple: “it cranks but won’t start.” My first step was to connect the scan tool, but it couldn’t establish communication with the PCM. This is a huge red flag. I immediately went to the PCM connectors and, using a wiring diagram, verified all power and ground circuits were good. With power going in but no communication coming out, the diagnosis was clear: internal PCM failure. Instead of a costly dealer replacement, we ordered a VIN-programmed module like this one. It arrived the next day, we performed the 30-minute security relearn, and the truck fired right up. The customer saved hundreds on dealer labor and programming fees.
Is Your Truck or SUV Showing These Symptoms?
A failing PCM can manifest in many ways. If you’re experiencing any of the following, a faulty module could be the culprit:
- âś” Persistent Check Engine Light (CEL)
- âś” Engine cranks but will not start
- âś” Poor or erratic engine performance
- âś” Decreased fuel economy
- âś” Harsh or incorrect automatic transmission shifting
- âś” Communication error codes, such as U0100
- âś” Internal module failure codes, like P0601, P0602, or P0606
Your Straightforward PCM Installation Guide
Installing your new PCM is a manageable job for a DIYer with basic tools. The most critical part is the security relearn procedure, which pairs the new module to your vehicle’s anti-theft system.
- Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post.
- Locate the PCM: On most of these GM trucks and SUVs, the PCM is located in the engine bay on the driver’s side, either under the battery tray or next to the air filter box.
- Disconnect and Remove: Carefully unplug the electrical connectors from the old PCM. They have locking tabs that need to be released. Once disconnected, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed PCM into place. Firmly reconnect the electrical connectors, ensuring they click and lock securely.
- Reconnect Battery: Re-attach the negative battery terminal.
- Perform Security Relearn (CRITICAL): This step is essential. Turn the key to the “ON” position (do not start the engine). The security light on the dash should be on or flashing. Leave the key on for 10-11 minutes, until the security light turns off. Turn the key off for 5 seconds. Repeat this process two more times for a total of three 10-minute cycles. After the third cycle, the vehicle will be paired with the new PCM and should start normally.
Verified Fitment For These GM Vehicles
This module is a direct replacement for service numbers 12582605, 89017750, 12589463, 12602802, 89017734, and 28042802. Please verify your part number or contact us with your VIN to ensure compatibility. This part fits a wide range of models, including:
- Cadillac Escalade, ESV, EXT (2003-2006)
- Chevrolet Avalanche 1500 (2003-2006)
- 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)
- GMC Envoy XL (2003)
- GMC Sierra 1500, 2500, 3500, Denali (2003-2007 Classic)
- GMC Yukon, Yukon XL 1500, Yukon XL 2500 (2003-2006)
- Hummer H2 (2003-2007)
- Isuzu Ascender (2003)
Frequently Asked Questions
Why do you need my VIN?
Your Vehicle Identification Number (VIN) is essential. We use it to load the exact, correct software and calibrations for your vehicle’s specific engine, transmission, and options. This ensures perfect compatibility and performance right out of the box.
Is this part difficult to install myself?
The physical replacement is straightforward, requiring only basic hand tools. The most important part is the Security Relearn Procedure, which requires patience but no special tools. Just follow our detailed instructions, and you can do it right in your driveway.
What if I don’t do the Security Relearn?
If the security relearn is not performed correctly, the vehicle’s anti-theft system will not recognize the new PCM, and the engine will not start. It is a mandatory step for this repair.
Will this fix my specific problem?
This PCM will resolve issues directly caused by a faulty original module, such as internal processor errors (P0601) or communication faults. While it fixes many common problems, proper diagnosis is always recommended to ensure you’re replacing the correct part.
What service numbers does this part replace?
This module is a direct replacement for several service numbers, including 12582605, 89017750, 12589463, 12602802, 89017734, and 28042802. Matching one of these numbers ensures compatibility.