Is your Hummer H2 or GM truck suddenly acting possessed? Frustrating issues like a persistent check engine light, erratic engine behavior, or a complete no-start condition can often be traced back to one single component: the Powertrain Control Module (PCM). As the central computer for your engine, when the PCM begins to fail, it can create a cascade of problems that are difficult to diagnose. This isn’t just an inconvenience; it’s a reliability issue that can leave you stranded.
This isn’t just a replacement part; it’s a comprehensive solution. We offer a reliable Powertrain Control Module, part number 12602802, that arrives at your door pre-programmed with the latest official GM software. By providing your Vehicle Identification Number (VIN) during checkout, we ensure the module is perfectly matched to your vehicle’s specific configuration. This eliminates the need for an expensive trip to the dealership for programming, saving you time and money and getting your truck back to peak operational health.
A Technician’s Notebook
I remember a 2005 Sierra 2500 with the 6.0L that came into my bay with a complaint of intermittent stalling and a check engine light. The owner had already replaced the crank sensor and a throttle position sensor, but the problem persisted. The codes were all over the place, including a nagging P0601 (Internal Control Module Memory Check Sum Error). After verifying the power and grounds to the PCM were solid—a critical first step—it was clear the module itself was the culprit. These internal processor faults are a dead giveaway. We installed a VIN-programmed PCM, performed the CASE relearn, and the truck ran like new. It’s a classic example of how a failing computer can mimic sensor or mechanical failures, costing owners time and money on unnecessary parts.
Is Your Truck Exhibiting These PCM Failure Signs?
A failing engine computer can manifest in numerous ways. If you’re experiencing any of the following, a faulty PCM could be the root cause:
- âś” Unexplained Check Engine Light with codes like P0601, P0602, P0606, or U0100 (Lost Communication with ECM/PCM).
- âś” Engine cranks but refuses to start.
- âś” Rough or unstable idling.
- âś” Sudden engine stalling or cutting out while driving.
- âś” Noticeable decrease in fuel economy.
- âś” Harsh or incorrect transmission shifting.
- âś” Communication issues with diagnostic scan tools.
A Straightforward Guide to Installation
Installing your new 2003-2007 Hummer H2 PCM is a manageable job for a confident DIYer. The module is typically located in the engine bay on the driver’s side, under or near the battery.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the PCM: On most of these GM trucks and SUVs, you’ll find the PCM mounted to a bracket on the driver’s side of the engine compartment, near the battery and fuse box.
- Disconnect Connectors: Carefully unlatch and remove the electrical wiring harness connectors from the old PCM. These connectors have locking tabs that need to be released before they can be unplugged. Avoid forcing them.
- 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 re-fasten the bolts.
- Reconnect Everything: Plug the wiring harness connectors firmly into the new module until they click into place. Reconnect the negative battery terminal.
- Security & Crank Relearn: After installation, you will likely need to perform a security relearn procedure (often called Passlock or Passkey relearn) and a Crankshaft Variation (CASE) relearn. These procedures can typically be done with a capable bi-directional scan tool or by following a specific sequence of key cycles. This is a critical final step for proper operation.
Verified Vehicle Compatibility
This module, service number 12602802, is a direct replacement for a wide range of GM trucks and SUVs. Please verify your part number or contact us with your VIN to confirm fitment. It is compatible with models including:
Cadillac: Escalade, Escalade ESV, Escalade EXT (2003-2006)
Chevrolet: Avalanche 1500, Silverado 1500/2500/3500, Suburban 1500/2500, Tahoe, SSR, Trailblazer EXT (2003-2007 Classic)
GMC: Sierra 1500/2500/3500, Sierra Denali, Yukon, Yukon XL 1500/2500, Envoy XL (2003-2007 Classic)
Isuzu: Ascender (2003)
Note: Specific year and engine options apply. It’s always best to match your original part or service number. Compatible service numbers include 89017750, 12582605, 12589463, 89017734, and 28042802.
Frequently Asked Questions
Do I need to do anything after I buy it?
Yes. After your purchase, you must send us your 17-digit VIN. We cannot program and ship your module without it. This ensures the PCM is correctly configured for your vehicle’s specific options and software requirements.
Is this really plug-and-play?
For the most part, yes. Because it’s pre-programmed to your VIN, it eliminates the most complex step. However, on most GM vehicles of this era, you will need to perform a security relearn and a Crankshaft Variation (CASE) relearn after installation for the vehicle to start and run correctly. Many high-end consumer scan tools can perform this, or it can be done by any professional mechanic.
Will this fix my check engine light?
If the check engine light is caused by an internal failure of the PCM (like code P0601), then yes, this module is the correct fix. However, it’s essential to properly diagnose your vehicle, as the check engine light can be triggered by hundreds of other issues, such as faulty sensors or wiring problems.
How do I find my original part number?
The part number is printed on a sticker on the PCM itself. You can cross-reference your number with the compatible service numbers listed: 89017750, 12582605, 12589463, 12602802, 89017734, or 28042802.