If your 2006 Chevy Trailblazer is experiencing frustrating issues like erratic shifting, stalling, a persistent Check Engine Light, or a complete no-start condition, the problem often points directly to a failing Powertrain Control Module (PCM). As the brain of your vehicle, a faulty PCM can disrupt everything. This isn’t just an inconvenience; it’s a critical component for your truck’s performance and reliability. We offer a dependable, straightforward solution: a replacement PCM, professionally programmed with the latest GM software updates specifically for your vehicle’s VIN.
From the Diagnostic Bay
I remember a 2006 Envoy with the 4.2L engine—mechanically identical to the Trailblazer—that came into my shop on a tow truck. The owner was frustrated; he’d already replaced the spark plugs and a coil pack trying to solve a random misfire and stalling problem. The scanner showed a P0601 code (Internal Control Module Memory Check Sum Error), a dead giveaway for PCM failure. The internal processor was failing, causing intermittent communication loss. We installed one of our pre-programmed modules, performed the quick security relearn, and the truck fired right up and idled perfectly. It’s a classic failure on these platforms, and a correct diagnosis saves hundreds on unnecessary parts.
Symptoms of a Failing 2006 Trailblazer PCM
A failing engine computer can manifest in numerous ways. If you’re noticing any of the following, it’s a strong indicator that your PCM needs attention. Look out for:
- ✔ Check Engine Light (CEL) illumination with communication error codes (e.g., P0601, P0606, U0100).
- ✔ The vehicle cranks but refuses to start.
- ✔ Unexplained stalling or rough idling, even after a tune-up.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ A noticeable drop in fuel economy.
- ✔ Failure to pass an emissions inspection due to module-related faults.
The Advantage: Programmed and Ready for Installation
The biggest hurdle when replacing a modern vehicle’s computer is the programming. Dealerships charge a premium for this service alone. We eliminate that step for you. Simply provide us with your vehicle’s 17-digit VIN during checkout, and our technicians will flash the module with the correct, updated GM-certified software for your specific Trailblazer. This ensures all systems communicate correctly, from the engine and transmission to the anti-theft system.
A Straightforward Guide to Installation
Replacing the PCM on your Trailblazer is a manageable job for a DIYer with basic tools. On the 4.2L models, it’s conveniently located in the engine bay.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work.
- Locate the PCM: Open the hood and find the PCM mounted on the driver’s side (LH) of the engine block. It’s a silver box with multiple large wiring harness connectors.
- Disconnect the Harnesses: Carefully unclip and remove the electrical connectors from the old PCM. These clips can be brittle, so work slowly.
- Remove the Old Module: Unbolt the PCM from its mounting bracket. There are typically a few bolts holding it in place.
- Install the New Module: Mount your new, pre-programmed PCM onto the bracket and securely re-fasten the bolts.
- Reconnect Everything: Plug the wiring harnesses firmly back into the new module until they click into place. Reconnect your battery terminal.
- Perform Security Relearn: You will likely need to perform a simple security relearn procedure. This typically involves turning the key to the ‘ON’ position for 10-15 minutes. We include instructions for this easy final step.
Verified Vehicle Compatibility
This module is a direct replacement for a wide range of GM vehicles and part numbers. Please verify your vehicle is on this list to ensure proper fitment. This unit is compatible with 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.
- Buick Rainier 2006: Electronic Control Module; (LH engine), 4.2L
- Chevrolet Colorado 2004-2006: Electronic Control Module; (RH firewall)
- Chevrolet Trailblazer 2006: Electronic Control Module; (LH engine), 4.2L
- Chevrolet Trailblazer EXT 2006: Electronic Control Module; (LH engine), 4.2L
- GMC Canyon 2004-2006: Electronic Control Module; (RH firewall)
- GMC Envoy 2006: Electronic Control Module; 4.2L (LH engine)
- GMC Envoy XL 2006: Electronic Control Module; (LH engine), 4.2L
- Hummer H3 2006: Electronic Control Module; (RH firewall)
- Isuzu Ascender 2006: Electronic Control Module; 4.2L (LH engine)
- Isuzu i-280 2006: Electronic Control Module; (RH firewall)
- Isuzu i-350 2006: Electronic Control Module; (RH firewall)
- Saab 9-7x 2006: Electronic Control Module; (LH engine), 6 cylinder
Frequently Asked Questions
Do I really need to provide my VIN?
Yes, absolutely. The Vehicle Identification Number (VIN) is essential for us to program the module with the exact software and calibrations for your vehicle’s specific options, engine, and transmission. This ensures perfect compatibility.
Is this a plug-and-play part?
Because we program it to your VIN before shipping, it is nearly plug-and-play. The only additional step required after installation is a simple security relearn procedure, which takes about 10-15 minutes and requires only your ignition key. Instructions are included.
Will this fix my specific problem?
This module is a direct solution for failures internal to the PCM, often indicated by codes like P0601 or other communication faults. While it resolves the most common electronic issues, always ensure your vehicle’s mechanical and wiring systems are in good working order for a complete repair.
What if my original part number is not 19209820?
No problem. This module is a hardware equivalent and direct replacement for the long list of part numbers shown in the compatibility section. As long as your original number is on that list, this module will work perfectly once programmed to your VIN.