Is Your 2006 Envoy or Trailblazer Acting Possessed?
If you’re dealing with frustrating and unpredictable issues on your 2006 GMC Envoy, Chevy Trailblazer, or another GM vehicle with the 4.2L engine, you know how maddening it can be. One day it runs fine, the next it won’t start, or it stalls at a stoplight. As a technician with over two decades of experience under the hood of these exact trucks, I’ve seen it all. The Powertrain Control Module (PCM), the central computer for your engine and transmission, is a very common point of failure on this platform.
Common Symptoms of a Failing 2006 GM PCM
A faulty PCM can manifest in ways that might seem unrelated, often leading DIYers and even some shops down an expensive rabbit hole of replacing perfectly good sensors. If you’re noticing any of the following, your PCM should be at the top of your suspect list:
- ✔ No-start condition where the engine cranks but won’t fire up.
- ✔ Stalling for no reason, either while driving or at idle.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ A persistent Check Engine Light with communication error codes (like U-codes).
- ✔ Inaccurate or non-functioning dashboard gauges.
- ✔ Reduced power or poor fuel economy that can’t be explained by other issues.
Expert Pro Tip: Check Your Grounds First!
Before you condemn your PCM, do yourself a favor and check the main ground connections. On these GMT360 platform trucks (Envoy, Trailblazer, etc.), there’s a critical ground point on the engine block near the starter and another on the frame rail. Over the years, I’ve seen dozens of vehicles come into my bay with a “bad PCM” diagnosis that was actually just a loose or corroded ground strap causing voltage drops and confusing the computer. A few minutes with a wrench can save you hundreds of dollars. If your grounds are clean and tight and the symptoms persist, then the PCM is the highly likely culprit.
The Direct Solution: A VIN-Programmed PCM
This isn’t just a replacement part; it’s a complete solution. This Powertrain Control Module is meticulously tested and then programmed specifically to your vehicle using your unique Vehicle Identification Number (VIN). This is a critical step that many sellers skip. Without proper programming, the vehicle won’t start due to the anti-theft system (Passlock), and the engine and transmission won’t operate correctly.
We handle the complex part for you. By loading the latest GM-certified software calibrations, we ensure your vehicle benefits from any factory-issued fixes for drivability or performance issues. This means you get a component that is truly ready for installation right out of the box.
- ✔ No Dealer Visit Required: Arrives programmed and ready to install, saving you time and the high cost of dealership programming.
- ✔ Latest GM Software: We flash the module with the newest updates for optimal performance and reliability.
- ✔ Guaranteed Compatibility: By using your VIN, we ensure a perfect software match for your specific options and systems.
- ✔ Solves Common Issues: Directly addresses the root cause of many frustrating electrical and drivability problems.
Installation Process
On most of the compatible vehicles like the 2006 Envoy or Trailblazer with the 4.2L engine, the PCM is conveniently located on the driver’s side of the engine compartment. After disconnecting the battery, you simply unplug the electrical connectors, unbolt the old module, and install the new one. Once connected and the battery is reconnected, you may need to perform a simple security relearn procedure, which can typically be done without any special tools. This restores communication between the new PCM and your vehicle’s security system.
Guaranteed Fitment for Part Number 19209820
This module is a direct replacement for part number 19209820 and a host of other interchangeable numbers. Please verify the part number on your existing module matches one in our list below. This unit is compatible with the following vehicles:
- ✔ 2006 Buick Rainier: 4.2L (Located LH engine)
- ✔ 2004-2006 Chevy Colorado: (Located RH firewall)
- ✔ 2006 Chevy Trailblazer & Trailblazer EXT: 4.2L (Located LH engine)
- ✔ 2004-2006 GMC Canyon: (Located RH firewall)
- ✔ 2006 GMC Envoy & Envoy XL: 4.2L (Located LH engine)
- ✔ 2006 Hummer H3: (Located RH firewall)
- ✔ 2006 Isuzu Ascender: 4.2L (Located LH engine)
- ✔ 2006 Isuzu i-280 & i-350: (Located RH firewall)
- ✔ 2006 Saab 9-7x: 6 Cylinder (ID 12569773 or 12597521, Located LH engine)
This part replaces the following part numbers: 12569773, 12588650, 12589311, 12589585, 12591647, 12591648, 12593531, 12593532, 12594430, 12594431, 12596783, 12596784, 12597521, 12597776, 12597777, 12600818, 12604438, 12604439, 12606369, 12606373, 12606374, 12606398, 12606399, 19209820, 19209821.
To complete your order, simply provide us with your vehicle’s VIN at checkout. We’ll take care of the rest, getting a fully programmed, ready-to-install PCM shipped directly to you.