Restore Your Trailblazer’s Shifting Performance
If your 2006-2009 Chevrolet Trailblazer is suffering from harsh shifting, getting stuck in gear, or throwing transmission codes, the culprit is often a failing Transmission Control Module (TCM). As a technician with over 20 years of experience, I’ve seen firsthand how a faulty TCM can cripple a perfectly good transmission. This T42 TCM, part number 24239224, is the definitive solution, acting as the ‘brain’ for your automatic transmission by precisely managing shift points, torque converter clutch engagement, and line pressure.
What sets this module apart is our expert VIN programming service. Before we ship it, we load it with the latest GM-approved software specific to your Trailblazer’s VIN. This means it arrives ready for a true plug-and-play installation, eliminating the need for an expensive trip to the dealership for programming. This is the same process we use in our shop to guarantee a fast, reliable repair that gets our customers back on the road with confidence. A faulty module doesn’t just cause annoying driving behavior; it can lead to premature transmission wear and even catastrophic failure. By replacing your old unit with this quality-tested 2006-2009 Trailblazer TCM, you’re not just fixing a symptom—you’re protecting your vehicle’s most expensive component.
Case Study: The Ghost in the Transmission
A customer brought in a 2008 Trailblazer with a maddeningly intermittent problem. It would drive perfectly for days, then suddenly slam into gear or refuse to shift out of 2nd. They had already replaced two shift solenoids at another shop with no luck. After connecting my scan tool, I noticed erratic data from the TCM, but no hard codes. Experience told me this was a classic sign of internal module failure. We installed one of our VIN-programmed T42 modules, and the problem vanished instantly. The fix wasn’t in the transmission itself, but in its electronic controller. This is a common scenario for these vehicles.
Is Your Trailblazer Exhibiting These Telltale Signs?
A failing TCM will give you clear warnings. If you’re experiencing any of the following, it’s time to consider a replacement. Ignoring these symptoms can lead to more costly transmission damage down the line.
- ✔ Harsh, banging, or erratic gear shifts.
- ✔ Vehicle is stuck in “limp mode” (usually 2nd or 3rd gear).
- ✔ Check Engine Light or Transmission Warning Light is on with codes like P0700, P0750, or other solenoid-related DTCs.
- ✔ Delayed engagement when shifting from Park to Drive or Reverse.
- ✔ Complete failure to upshift or downshift.
- ✔ Poor fuel economy and a feeling of sluggish performance.
- ✔ Intermittent loss of communication with the TCM.
A Straightforward Guide to Installation
One of the best features of this part is its simple installation, which most DIYers can complete in under 30 minutes with basic hand tools. This 2006-2009 Trailblazer TCM is designed for a direct fit.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent electrical shorts and help reset the system.
- Locate the Module: On the Trailblazer and Envoy, the TCM is typically found in the left-hand (driver’s side) of the engine compartment.
- Disconnect and Remove: Carefully unplug the electrical connectors. Press the release tabs firmly. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed TCM into place and securely reconnect the electrical harnesses. You should hear a click.
- Reconnect and Verify: Reconnect the negative battery terminal. Start the vehicle and ensure the check engine light is off and the transmission shifts smoothly. We recommend using a basic scan tool to clear any stored historical codes for a clean slate.
Verified Compatibility for Your GM Vehicle
This T42 TCM is a direct replacement for part number 24239224 and is interchangeable with many other service numbers. While this page focuses on the 2006-2009 Trailblazer TCM, it also fits a wide range of other GM vehicles. Please verify your part number or consult the list below.
This part will fit these makes and models with these options:
- TRAILBLAZER 06-07 Transmission; (LH engine compartment), (8 cylinder)
- TRAILBLAZER 08-09 Transmission; (LH engine compartment)
- ENVOY 06-07 Transmission; (LH engine compartment), (8 cylinder)
- ENVOY 08-09 Transmission; (LH engine compartment)
- SAAB 9-7X 06-09 Transmission; (LH engine compartment)
- RAINIER 06-07 Transmission
- … and many other GM cars, trucks, and SUVs including Silverado, Tahoe, Yukon, Impala, H3, and more.
Frequently Asked Questions
Do I need to have this TCM programmed by a dealer?
No. We pre-program the module to your vehicle’s specific VIN before shipping. It arrives ready for immediate installation, saving you time and money.
Where is the TCM located on my 2007 Trailblazer?
On the 2006-2009 Trailblazer, the Transmission Control Module is located in the engine bay, on the driver’s side (LH side) near the firewall.
Is this a new or used part?
This is a high-quality, OEM-standard replacement part, tested for reliability and backed by our one-year warranty. It is not a used part from a junkyard.
Will this fix a P0700 trouble code?
A P0700 code is a general fault request from the TCM. While a faulty TCM is a very common cause, you should also check for related codes (like solenoid faults) to confirm the diagnosis. In many cases, replacing the TCM will resolve the P0700 code and the underlying issue.
Is there a core charge for my old part?
No, there is no core charge. You can keep your old module without the hassle of returning it.