If your 2006-2009 Chevrolet Trailblazer is suffering from erratic shifting, getting stuck in gear, or has thrown a transmission-related check engine light, you’re likely dealing with a failing Transmission Control Module (TCM). As a technician with over two decades of experience, I’ve seen firsthand how a faulty TCM can mimic a major mechanical failure, causing immense frustration for vehicle owners. The TCM is the electronic brain of your automatic transmission, and when it fails, communication breaks down, leading to poor performance and potential damage.
This T42 Transmission Control Module is the definitive solution for your vehicle’s shifting woes. It arrives expertly pre-programmed to your Trailblazer’s specific Vehicle Identification Number (VIN), making it a true plug-and-play repair. This crucial step eliminates the need for expensive and time-consuming programming at a dealership. You can restore the crisp, predictable shifting your vehicle had when it was new and regain confidence on the road. By replacing your faulty unit, you’re not just fixing a symptom; you’re addressing the root cause of issues like poor fuel economy and transmission stress.
Case Study: A Tricky Diagnosis
A customer brought in a 2008 Trailblazer with a classic complaint: it would intermittently slam into gear and sometimes refuse to shift past 2nd. They had already replaced two shift solenoids based on DTCs, but the problem persisted. After a quick data stream analysis, I noticed erratic voltage readings from the TCM. Instead of continuing to chase electrical ghosts, we installed one of our VIN-programmed T42 modules. The problem was solved instantly. This is a common scenario; the TCM is often the hidden culprit behind persistent solenoid codes.
Is Your Trailblazer Exhibiting These Telltale Signs?
A failing 2006-2009 Trailblazer TCM can manifest in several ways. If you’re experiencing any of the following, it’s a strong indicator that your module needs replacement:
- ✔ Harsh, banging shifts or delayed gear engagement.
- ✔ The vehicle is stuck in “limp mode” (usually 2nd or 3rd gear).
- ✔ Check Engine Light is on with transmission codes like P0700, P0750, P0753, or other solenoid-related faults.
- ✔ Failure to upshift or downshift properly, leading to high RPMs or bogging.
- ✔ A sudden drop in fuel efficiency.
- ✔ Complete loss of communication with the transmission.
Your Step-by-Step Installation Guide
For the confident DIYer or professional mechanic, installing this module is a straightforward process that typically takes less than 30 minutes.
- 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 2006-2009 Trailblazer, the TCM is typically found in the engine compartment on the left-hand (driver’s) side.
- Disconnect and Remove: Carefully unplug the electrical connectors from the old module. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, VIN-programmed TCM into place and securely reconnect the electrical harnesses. Ensure they click into place.
- Final Steps: Reconnect the battery terminal. While the module is plug-and-play, it’s best practice to use a standard OBD2 scan tool to clear any stored diagnostic trouble codes from the vehicle’s memory.
Verified Fitment for Your Vehicle
This module is a direct replacement for part number 24255280 and is compatible with a wide range of General Motors vehicles. While this page focuses on the 2006-2009 Trailblazer TCM, it also fits the following models (please verify location from the list):
- TRAILBLAZER 06-09 (LH engine compartment)
- ENVOY 06-09 (LH engine compartment)
- SAAB 9-7X 06-09 (LH engine compartment)
- RAINIER 06-07
- SSR 05-06 (front LH frame)
- SILVERADO, SIERRA 1500/2500 07-13 (next to battery)
- TAHOE, YUKON, SUBURBAN, AVALANCHE 07-09 (next to battery)
- EXPRESS, SAVANA VANS 06-14 (RH engine compartment)
- COLORADO, CANYON 08-12 (RH rear engine compartment)
- HUMMER H3 08-10 (RH rear engine compartment)
- IMPALA 06-11 (lower air cleaner housing)
- GRAND PRIX 06-08 (lower air cleaner housing)
- LACROSSE / ALLURE 06-09 (lower air cleaner housing)
- LUCERNE 06-11 (LH engine compartment)
- CADILLAC DTS 06-11 (RH front engine compartment)
- COBALT, G5, G6, PURSUIT 06-10 (LH strut tower)
- HHR 06-11 (LH engine compartment)
- MALIBU 06-10 (LH frame rail)
- SATURN AURA, ION, VUE (various locations, check list)
- UPLANDER, MONTANA, TERRAZA 06-09 (LH strut tower)
Frequently Asked Questions
What does VIN programming actually do?
VIN programming loads your vehicle’s specific software and calibrations onto the module before it ships. This ensures the TCM works perfectly with your engine, transmission, and options, eliminating the need for a dealership visit. It’s a key part of making this a plug-and-play solution.
Is this a new or used part?
This is a high-quality, fully tested OEM-standard part, backed by our one-year warranty, ensuring reliability and longevity. We do not sell used or junkyard electronics.
Will this fix my transmission slipping?
If the slipping is caused by incorrect signals or commands from a faulty TCM, then yes, this module can resolve it. However, slipping can also be a sign of internal mechanical wear (like worn clutches). A proper diagnosis is always recommended.
Do I need to send my old TCM back (core charge)?
No, there is no core charge for this part. You can keep or dispose of your old module without the hassle of returning it.
What if I order the wrong part?
We’re here to help! Providing your VIN at checkout allows us to double-check compatibility. If you have any doubts, please contact our expert support team before ordering to ensure you get the right part the first time.