Restore Peak Performance to Your GM Truck or SUV
Is your 2004 GMC Yukon XL 2500 or another compatible GM vehicle suffering from frustrating issues like stalling, erratic shifting, poor fuel mileage, or a persistent Check Engine Light? The Powertrain Control Module (PCM), the electronic brain of your engine and transmission, is often the culprit. Over time, heat cycles and vibrations can cause internal components to fail, leading to a host of performance problems. This isn’t just an annoyance; it’s a critical failure that can leave you stranded. This replacement PCM is the reliable, straightforward solution to get your vehicle running properly again.
We take the guesswork and dealer-level expense out of the equation. Unlike a generic module from a parts store, this unit arrives at your door pre-programmed with the latest official GM software updates, specifically matched to your vehicle’s VIN. This ensures seamless communication between all your vehicle’s systems, restoring the original drivability and efficiency you expect. Simply provide your VIN at checkout, and we handle the complex programming for you.
Is Your GM Vehicle Showing These Signs?
- ✔ Check Engine Light is on with diagnostic trouble codes (DTCs) like P0601, P0602, P0606 (Internal Control Module Failure).
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained stalling or rough idling, especially when warm.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Communication errors with scan tools (U-codes).
- ✔ Other electronic systems acting erratically due to network issues.
From the Diagnostic Bay
I remember a 2004 Sierra 2500 with the 8.1L that came into my shop with a maddeningly intermittent no-start condition. The owner had already replaced the battery, crank sensor, and fuel pump. It would run fine for days, then refuse to start. After hours of diagnostics, we found the problem was heat-related. When the engine bay got hot, the PCM would internally short, cutting communication. A tap on the module would sometimes bring it back to life. Replacing the faulty module with a correctly programmed 2004 Yukon XL 2500 PCM (the same P59 controller) solved the problem permanently. These modules are robust, but after nearly two decades, heat is their biggest enemy.
A Straightforward Guide to Installation
- ✔ Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent accidental reconnection.
- ✔ Locate the PCM: On most trucks like the Yukon XL 2500, the PCM is located under the hood on the driver’s side, near the battery, often in a black plastic bracket. On vans, it’s typically in the LH rear of the engine compartment.
- ✔ Disconnect the Connectors: Carefully unplug the electrical harness connectors from the old PCM. These connectors have locking tabs that need to be released. Do not force them.
- ✔ Remove the Old Module: Unbolt the PCM from its mounting bracket. Keep the hardware as you will reuse it.
- ✔ Install the New Module: Mount your new, pre-programmed PCM into the bracket and secure it with the original hardware.
- ✔ Reconnect Everything: Firmly plug the harness connectors into the new PCM until they click into place. Reconnect the negative battery terminal.
- ✔ Perform Security Relearn: You will need to perform a security relearn procedure (often called a CASE relearn). This typically involves turning the key to ‘ON’ for 10-15 minutes, then ‘OFF’, and repeating this cycle 2-3 times until the security light goes out. This allows your vehicle’s anti-theft system to recognize the new PCM.
Will This Fit My Vehicle?
This module is a direct replacement for part numbers 89017739 and 12586243 and is confirmed to fit the following 2004 models. Please verify your specific engine and options.
- AVALANCHE 2500: (LH front under battery)
- ASTRO / SAFARI (GMC): (LH front by battery)
- BLAZER S10/JIMMY S15: (RH front engine compartment)
- CORVETTE: (RH engine compartment)
- CTS (2004-2005): V-Series (RH engine compartment)
- ENVOY XL / XUV, TRAILBLAZER EXT, RAINIER: 5.3L (next to air box)
- EXPRESS / SAVANA VAN (1500, 2500, 3500): (LH rear engine compartment)
- GTO: (LH engine)
- S10/S15/SONOMA: (RH front engine compartment)
- SIERRA / SILVERADO 1500: 4.3L (LH front under battery)
- SIERRA / SILVERADO 2500/3500: 8.1L Gasoline (LH front under battery)
- SSR: (next to air box)
- SUBURBAN 2500: 8.1L (LH front under battery)
- YUKON XL 2500: 8.1L (LH front under battery)
Frequently Asked Questions
Do I need to do any programming myself?
No. We flash the module with the latest GM calibration for your specific VIN before shipping. The only procedure you may need to perform is the security relearn, which requires no special tools.
What is a security relearn or CASE relearn?
This is a simple procedure that syncs the new PCM with your vehicle’s anti-theft system. Instructions are included, and it typically involves a few key cycles. This must be done for the vehicle to start and run with the new module.
Is this a new or used part?
This is a high-quality, tested, and verified replacement module that is guaranteed to perform to OEM standards. It comes programmed and ready for installation.
What information do you need from me?
After you place your order, you must provide us with your vehicle’s 17-digit Vehicle Identification Number (VIN). We cannot program or ship the module without it.
Will this fix my transmission problems?
If your transmission issues, like poor shifting, are caused by a faulty PCM, then yes, this will resolve them. The PCM controls both engine and transmission functions, so a failing module often causes issues with both.