Restore Peak Performance to Your GM Truck or SUV
Is your 2004 GMC Sierra 2500, or another compatible GM vehicle, suffering from perplexing issues like a persistent check engine light, rough idling, poor fuel mileage, or even a no-start condition? These are classic signs of a failing Powertrain Control Module (PCM), the central computer that manages your engine’s performance. This direct-replacement PCM, part number 12586242, is the definitive solution to restore your vehicle’s reliability and drivability. It arrives at your door fully programmed to your vehicle’s specific VIN with the latest GM software updates, eliminating the need for expensive dealership programming.
From the Diagnostic Bay
We recently had a 2004 Silverado 6.0L in the shop with a nagging P0300 (Random Misfire) code. The owner had already replaced the spark plugs, wires, and even a coil pack with no success. After hours of diagnostics, we hooked up a scope to the injector circuits and found that the driver for cylinder 3 inside the original PCM was weak and intermittent. It wasn’t faulty enough to set a specific injector code, but it was enough to cause a misfire under load. Installing a correctly programmed 2004 Sierra 2500 PCM like this one resolved the issue immediately. It’s a reminder that sometimes the problem lies not with the sensors or coils, but with the brain controlling them.
Is Your PCM Failing? Common Symptoms
- ✔ Persistent Check Engine Light (CEL) that won’t clear.
- ✔ Unexplained drop in fuel economy.
- ✔ Engine stumbling, hesitating, or misfiring during acceleration.
- ✔ Rough or erratic idling.
- ✔ Harsh or incorrect automatic transmission shifting.
- ✔ Intermittent starting problems or a complete no-start condition.
- ✔ Failed emissions test.
The Critical Role of Your 2004 Sierra 2500 PCM
The PCM is the undisputed command center of your vehicle’s powertrain. It constantly analyzes data from dozens of sensors—like the crankshaft position sensor, oxygen sensors, and mass airflow sensor—to make instantaneous decisions. It precisely controls the fuel injectors, ignition timing, and transmission shift points to ensure optimal power, efficiency, and emissions control. When it begins to fail, this delicate balance is disrupted, leading to the frustrating symptoms you may be experiencing. Replacing it with a properly functioning, correctly programmed unit is essential for your vehicle’s health.
Simple Installation Process
This module is designed for a straightforward installation. Once you place your order, simply provide us with your vehicle’s VIN. Our technicians will flash the module with the exact factory software for your truck. On most GM trucks like the Sierra and Silverado, the PCM is located in the engine bay on the driver’s side, often under or near the battery. After disconnecting the battery, you can unbolt the old module, disconnect the wiring harnesses, and install the new one in its place. In many cases, the vehicle will start and run perfectly. However, a simple security relearn procedure (often called a CASE relearn) may be required, which can be done by a qualified technician with a scan tool to ensure perfect communication with your vehicle’s anti-theft system.
Guaranteed Compatibility
This module is a direct replacement for service number 12586242 and is also fully compatible with the following service numbers: 19299226, 89017738, YFKD, YFKF, YFKH, YFKJ, YFKX, YFXL, YFXM, YFXN, YFXP, and YHTN. It fits a wide array of 2004 GM models, including:
- GMC Sierra & Yukon / Yukon XL (1500, 2500, 3500)
- Chevrolet Silverado & Suburban / Tahoe (1500, 2500, 3500)
- Chevrolet Avalanche & SSR
- Cadillac Escalade (Base, ESV, EXT)
- GMC Envoy & Chevrolet Trailblazer
- Buick Rainier & Isuzu Ascender
- Hummer H2
Please verify your service number to ensure a perfect match for your application.
Frequently Asked Questions
Why do I need to provide my VIN?
Your Vehicle Identification Number (VIN) allows us to program the PCM with the precise software calibration for your truck’s engine, transmission, and factory options. This ensures seamless integration and optimal performance without a trip to the dealer.
Is this module difficult to install?
The physical installation is straightforward for anyone with basic mechanical skills. It involves disconnecting the battery and swapping the module. However, a security relearn procedure may be necessary afterward, which typically requires a professional scan tool to complete.
Where is the PCM located on my 2004 Sierra 2500?
On most 2004 GM full-size trucks, including the Sierra 2500, the PCM is located in the engine compartment on the driver’s side, mounted near the battery tray or fender well.
Will this fix my check engine light?
If the PCM itself is the cause of the fault codes triggering your check engine light, then yes, this replacement part will solve the problem. It is crucial to properly diagnose the issue first, as the light could be caused by a faulty sensor or other component.
What if my original part number is different from 12586242?
No problem. This PCM is a consolidated replacement for multiple service numbers. As long as your original module has one of the compatible numbers listed (e.g., YFKD, YFXL, YHTN, etc.), this unit will be the correct replacement for your vehicle.