2003-2006 Yukon XL 2500 PCM 12602802 Programmed to Your VIN

Is Your Truck Running Rough? Get a Reliable, Programmed Solution.

If your 2003-2006 GMC Yukon XL 2500 is suffering from a persistent check engine light, erratic shifting, stalling, or a frustrating no-start condition, a failing Powertrain Control Module (PCM) is often the culprit. As the central computer for your engine and transmission, its health is non-negotiable. This isn’t just a replacement part; it’s a professionally programmed, direct-fit solution designed to restore your vehicle’s performance and reliability, all without a trip to the dealership.

Over my 20+ years in the bay, I’ve seen countless GMT800-platform trucks and SUVs with these exact issues. Just last month, a customer’s ’05 Sierra 2500 with the 6.0L—which uses this exact same PCM—came in with a random no-start that had stumped two other shops. The issue was a heat-soaked PCM causing intermittent communication loss. After swapping in one of our pre-programmed modules, the truck fired right up and has been running perfectly ever since. This is the fix that works.

The Critical Importance of VIN Programming

Simply installing a used or unprogrammed module will not work. Your vehicle’s Vehicle Identification Number (VIN) contains specific information about its engine, transmission, and options. We flash this module with the latest official GM software updates tied directly to your VIN. This ensures all systems communicate correctly, restoring factory performance, fuel economy, and emissions compliance.

Common Symptoms of a Failing PCM:

• ✔ Persistent Check Engine Light (CEL) with communication-related codes (U-codes)
• ✔ Harsh or erratic automatic transmission shifting
• ✔ Engine stalling, stumbling, or misfiring
• ✔ Complete no-start or intermittent starting problems
• ✔ Reduced fuel economy
• ✔ Failure to pass emissions testing

Plug-and-Play Installation: No Dealer Visit Required

We make this repair as straightforward as possible. Once you receive your VIN-programmed module, you can install it yourself with basic hand tools. Here’s a typical installation process for these GM trucks:

1. Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post.
2. Locate the PCM: On most models like the Yukon, Silverado, and Sierra, the PCM is located in the engine bay, on the driver’s side, typically under or next to the battery tray in a black plastic bracket.
3. Disconnect the Harnesses: Carefully lift the colored locking levers on each wiring harness connector. This will unseat the connector from the module. There are usually two or three connectors.
4. Remove the Old Module: Unclip or unbolt the PCM from its mounting bracket. It should slide out easily.
5. Install the New Module: Seat your new, pre-programmed PCM into the bracket and reconnect the wiring harnesses. Press them in firmly and push the locking levers back down until they click into place.
6. Reconnect the Battery: Re-attach the negative battery terminal. The vehicle may need to run for a few minutes for the idle to stabilize. No further security or CASE relearn is typically required.

Guaranteed Fitment for Your GM Truck or SUV

This module, part number 12602802, is a direct replacement for a wide range of GM vehicles and supersedes multiple service numbers, including 89017750, 12582605, 12589463, and 89017734. While this listing is focused on the 2003-2006 Yukon XL 2500 PCM, it is also the correct part for many other models such as the Cadillac Escalade, Chevy Silverado, Suburban, Tahoe, Hummer H2, and GMC Sierra. Please verify your part number or consult the compatibility list to ensure this is the correct module for your specific application.