If you’re dealing with frustrating and unpredictable issues in your 2003-2007 HUMMER H2, the Powertrain Control Module (PCM) is often the culprit. As a seasoned technician, I’ve seen firsthand how a failing PCM can cause a cascade of problems that are difficult to diagnose. This isn’t just a component; it’s the brain of your vehicle, managing everything from fuel mixture and ignition timing to transmission shift points. When it falters, your H2’s performance and reliability suffer.
We offer a dependable solution: a direct-fit PCM, service number 12589463, that arrives at your door programmed and ready for installation. We take your vehicle’s unique VIN and flash the module with the latest, most stable software updates from GM. This eliminates the need for an expensive trip to the dealership for programming. You get a reliable part that restores your vehicle’s factory-spec operation, solving those nagging issues and getting you back on the road with confidence.
A Technician’s Notebook: The Ghost in the H2
I had a 2005 HUMMER H2 roll into my bay that was giving its owner fits. The complaint was intermittent stalling at stoplights and a transmission that would occasionally refuse to shift out of first gear. The owner had already replaced the battery and alternator, but the problems persisted. No consistent trouble codes were stored, just a few random communication errors. After checking all the power and ground connections to the PCM, I hooked up my scope. I noticed the 5-volt reference signal to the throttle position sensor would momentarily drop out right before a stall. This pointed directly to an internal fault in the PCM. We installed one of our pre-programmed modules, performed the security relearn, and the H2 ran perfectly. It’s a classic example of how a failing 2003-2007 HUMMER H2 PCM can create phantom problems that seem unrelated.
Is Your Truck Showing These Symptoms?
A failing PCM can manifest in many ways. If you’re experiencing any of the following, it’s a strong indicator that your engine computer needs attention:
- ✔ Check Engine Light is on with codes like P0601 (Internal Control Module Memory Check Sum Error) or P0606 (PCM Processor Fault).
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained stalling or rough idling, especially when warm.
- ✔ A noticeable drop in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Communication errors with other modules on the vehicle (e.g., ABS, BCM).
- ✔ Loss of power or sluggish acceleration.
A Straightforward Guide to Installation
Replacing the PCM on these GM trucks is a job most DIYers can handle with basic tools. Here’s a general guide to get you started:
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the PCM: On most of these vehicles, including the HUMMER H2, the PCM is located in the engine bay, on the driver’s side, under or next to the battery tray.
- Disconnect the Connectors: Carefully unclip and remove the electrical wiring harnesses from the old PCM. These connectors have locking tabs that need to be released before they can be pulled out.
- Remove the Old Module: Unbolt the PCM from its mounting bracket and remove it from the vehicle.
- Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and securely bolt it in place.
- Reconnect Everything: Plug the wiring harnesses back into the new module, ensuring they click securely into place. Reconnect the negative battery terminal.
- Perform Security Relearn: You will need to perform a simple security relearn procedure (often called a ‘key-on’ relearn) to sync the new PCM with your vehicle’s anti-theft system. This typically takes about 30 minutes and does not require a special scan tool.
Verified Vehicle Compatibility
This module is a direct replacement for service numbers 89017750, 12582605, 12589463, 12602802, 89017734, and 28042802. It is confirmed to fit the following GM vehicles:
- Cadillac Escalade, ESV, EXT: 2003-2006
- Chevrolet Avalanche 1500: 2003-2006
- Chevrolet Silverado 1500, 2500, 3500: 2003-2007 (Classic style for ’07)
- Chevrolet SSR: 2003
- Chevrolet Suburban 1500, 2500: 2003-2006
- Chevrolet Tahoe: 2003-2006
- Chevrolet Trailblazer EXT: 2003 (5.3L)
- GMC Envoy XL: 2003 (5.3L)
- GMC Sierra 1500, 2500, 3500: 2003-2007 (Classic style for ’07)
- GMC Sierra Denali: 2003-2007 (Classic style for ’07)
- GMC Yukon, Yukon XL 1500, Yukon XL 2500: 2003-2006
- HUMMER H2: 2003-2007
- Isuzu Ascender: 2003 (5.3L)
Please provide your VIN upon checkout to ensure we program the correct software for your specific vehicle and its options.
Frequently Asked Questions
Do I need to do anything after installing this PCM?
Yes. While the main engine and transmission programming is done for you, you must perform a security relearn procedure. This syncs the new PCM to your vehicle’s anti-theft system and keys. It’s a simple process that typically involves turning the key to the ‘ON’ position for 10-12 minutes, then off, and repeating two more times. Instructions will be included.
How do I provide my VIN?
After you complete your purchase, you can send us a message with your 17-digit Vehicle Identification Number (VIN). We cannot ship your module until we receive this information, as it is essential for correct programming.
Will this fix my check engine light?
If the check engine light is caused by a faulty PCM (e.g., codes P0601, P0606), then this replacement module will solve the problem. However, if the light is on due to a bad sensor or other mechanical issue, you will still need to diagnose and repair that separate problem.
Is this a brand new part?
This is a high-quality, fully tested replacement part that meets or exceeds original equipment specifications. It is loaded with new, VIN-matched GM software to ensure reliability and proper function.
What if I have an aftermarket intake or exhaust?
Our programming service installs the latest factory GM calibration for your specific VIN. It is not designed for vehicles with significant aftermarket modifications that alter engine airflow or operation. This module is intended to restore stock performance and reliability.