Is Your 2006 Trailblazer or Envoy Running Rough?
If you’re dealing with frustrating and unpredictable issues on your 2006 Trailblazer, Envoy, or another GM truck with the 4.2L engine, a failing Powertrain Control Module (PCM) is one of the most common culprits I see in my shop. As a technician with over two decades of experience, these symptoms are all too familiar. You might be experiencing:
- A crank-but-no-start condition that happens randomly.
- The engine stalling for no apparent reason, either at idle or while driving.
- A persistent Check Engine Light with communication error codes.
- Your scan tool is unable to connect or communicate with the PCM.
- Harsh or erratic automatic transmission shifting.
- Reduced engine power or poor fuel economy.
Why the Original PCM Fails
The PCM is the electronic brain of your vehicle, controlling everything from the fuel injectors and spark plugs to the transmission shift points. On these GMT360 platform vehicles (like the Trailblazer, Envoy, Rainier), the PCM is located on the driver’s side of the engine bay. Over years of heat cycles and engine vibration, the delicate internal circuits and solder joints can degrade and fail, leading to the intermittent problems that are so difficult to diagnose.
A Real-World Diagnosis Story
A customer’s 2006 GMC Envoy with the 4.2L was towed to my shop last month. The owner had already replaced the battery and checked the fuel pump, but it would still crank without starting about half the time. My diagnostic scanner couldn’t establish a link with the PCM. After confirming the module had proper power and ground at the connectors—a critical first step—it was clear the PCM itself was internally shorted. This is a story I’ve seen play out hundreds of times on these otherwise reliable trucks. Replacing the PCM with a correctly programmed unit solved the problem instantly.
The Simple, Reliable Solution: A VIN-Programmed PCM
This isn’t just a replacement part; it’s a complete solution. We take a fully tested, functional PCM and flash it with the latest official GM software calibration for your specific vehicle. The process is simple:
- You purchase this module.
- You provide us with your vehicle’s 17-digit VIN.
- Our technicians program the module to match your VIN’s exact factory configuration.
- We ship you a module that is ready for installation, eliminating the need for an expensive trip to the dealership for programming.
Guaranteed Compatibility and Fitment
This module is a direct replacement for a wide range of GM vehicles and part numbers. If your old module has any of the following numbers, this part is the correct replacement for you:
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
This PCM fits the following models:
- 2006 TRAILBLAZER / TRAILBLAZER EXT (4.2L)
- 2006 ENVOY / ENVOY XL (4.2L)
- 2006 BUICK RAINIER (4.2L)
- 2006 ISUZU ASCENDER (4.2L)
- 2006 SAAB 9-7X (6 cylinder)
- 2006 HUMMER H3
- 2004-2006 COLORADO / CANYON
- 2006 ISUZU I-280 / I-350
Installation is Straightforward
After installing the module, you will need to perform a security relearn procedure to sync the new PCM with your vehicle’s anti-theft system. This is a simple process that does not require special tools and typically takes about 30 minutes. Instructions are readily available online, or your local mechanic can perform it quickly. This final step ensures your truck starts and runs as it should, getting you back on the road with confidence.