Restore Your Vehicle’s Brain, Restore Your Drive
Is your 2004 Hummer H2, Silverado, or Sierra running rough, stalling, or refusing to start? A faulty Powertrain Control Module (PCM) can be the source of countless frustrating and hard-to-diagnose issues. This isn’t just a replacement part; it’s the definitive solution to get your truck or SUV back to factory-spec performance. We take the guesswork and dealership hassle out of the equation by pre-programming this unit specifically for your vehicle using your VIN. It arrives ready for installation, loaded with the latest GM software updates to ensure optimal engine performance, fuel economy, and transmission shifting.
Common Symptoms & Your Solution
If you’re experiencing any of the following, a failing PCM is the likely culprit. This module is the solution for:
- Check Engine Light (CEL) with various trouble codes (DTCs)
- Engine stalling, stumbling, or rough idling
- No-start or intermittent starting conditions
- Poor fuel mileage and reduced engine power
- Harsh or erratic automatic transmission shifting
- Communication errors with diagnostic scan tools
Replacing your old module with this professionally programmed 2004 Hummer H2 PCM is the most effective way to resolve these complex electronic issues and restore the reliability you depend on.
Features & Benefits
- ✔ VIN-Programmed for You: Arrives ready to install, flashed with your vehicle’s specific calibration. No expensive trip to the dealer is required for programming.
- ✔ Latest GM Software: We load the most current factory software, ensuring all performance and drivability enhancements from the manufacturer are included.
- ✔ Guaranteed Compatibility: This unit is a direct replacement for service number 12586242 and a wide range of other compatible part numbers, ensuring a perfect fit and function.
- ✔ Plug-and-Drive Installation: Once you perform the simple security relearn procedure (instructions included), your vehicle is ready to go.
- ✔ Restored Performance: Get back the smooth idle, crisp throttle response, and reliable operation you’ve been missing.
- ✔ This unit is backed by our one-year replacement warranty.
Expert Insight: The Importance of Correct Programming
In modern GM vehicles like yours, the PCM is more than just an engine controller; it’s the central command center. It manages everything from the fuel injectors and spark plugs to the transmission shift points and torque converter lockup. Using a generic, non-programmed module can lead to persistent performance issues, poor shifting, and even damage to other components. Our process ensures the module we send you is an exact digital match for your vehicle’s original equipment, providing seamless integration and restoring proper function from the moment you turn the key.
Frequently Asked Questions
Do I need to send you my old computer?
No, there is no core charge or need to send in your original module. This is a direct purchase.
Where do I provide my VIN?
After you complete your purchase, you will need to send us your 17-digit Vehicle Identification Number (VIN). We cannot program and ship your part without it.
Is this part difficult to install?
The physical installation is straightforward for someone with basic mechanical skills. It typically involves disconnecting the battery, unplugging the electrical connectors, and unbolting the old module. The most critical step after installation is the security relearn procedure, which can be done without special tools and takes about 30 minutes.
What is a security relearn or CASE relearn?
The security relearn (also called Passlock or VATS) syncs the new PCM with your vehicle’s anti-theft system, allowing the engine to start. A Crankshaft Variation Relearn (CASE) may also be required with a scan tool to fine-tune engine timing and prevent a check engine light for code P1336, though the vehicle will run and drive without it.
How do I know if this fits my vehicle?
This 2004 Hummer H2 PCM fits a wide variety of GM trucks and SUVs from that model year. The best way to confirm is to match your original module’s service number to 12586242 or any of the other compatible numbers listed in the fitment data. If you’re unsure, just send us a message with your VIN and we can verify compatibility for you.