Restore Smooth Shifting to Your Trailblazer EXT
Is your 2006 Chevrolet Trailblazer EXT suffering from harsh shifting, delayed gear engagement, or getting stuck in limp mode? These are classic signs of a failing Transmission Control Module (TCM). As the electronic brain of your automatic transmission, a faulty TCM can disrupt communication, leading to poor performance, decreased fuel economy, and potential transmission damage. This T42 series TCM, part number YNXS, is the definitive solution, arriving pre-programmed to your vehicle’s specific VIN for a true plug-and-play repair.
Case Study: A Tricky Diagnosis
I remember a 2006 Trailblazer that came into my shop with a P0753 code for a Shift Solenoid ‘A’ Electrical fault. The owner had already replaced the solenoid twice with no luck. The transmission would shift erratically, especially when hot. After checking the wiring harness for continuity, we focused on the TCM. These T42 modules are known to develop internal solder joint failures from heat cycles, causing intermittent connections. We swapped in a VIN-programmed module, cleared the codes, and the problem was gone. The solenoid was never the issue; it was the TCM failing to command it properly. This replacement part directly addresses that common point of failure.
Is Your Trailblazer Exhibiting These Transmission Problems?
A failing TCM doesn’t always mean a complete transmission failure. Catching the signs early can save you from a much more expensive repair down the line. Look out for these common indicators:
- ✔ Harsh, jerky, or erratic gear changes.
- ✔ The vehicle is stuck in a single gear (often 2nd or 3rd) known as “limp mode.”
- ✔ Check Engine Light or Transmission Warning Light is illuminated.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700 (Transmission Control System Malfunction), P0750, P0753, or other solenoid-related codes.
- ✔ Delayed engagement when shifting from Park to Drive or Reverse.
- ✔ A noticeable drop in fuel efficiency.
Your Straightforward 30-Minute Installation Guide
Replacing the 2006 Trailblazer EXT Transmission Control Module is a job most DIYers can handle in their own driveway. On your vehicle, it’s typically located in the left-hand (driver’s side) engine compartment.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery to prevent electrical shorts and help reset the system.
- Locate the Module: Find the TCM in the LH engine compartment. It’s a silver box with electrical connectors.
- Disconnect and Remove: Carefully unclip the wiring harnesses. Then, unbolt the module from its mounting bracket.
- Install the New TCM: Bolt the new, VIN-programmed module into place. Securely reconnect the wiring harnesses, ensuring they click into place.
- Final Steps: Reconnect the battery terminal. While the module is plug-and-play, it’s best practice to use a basic OBD2 scan tool to clear any stored fault codes from the vehicle’s memory.
Verified Fitment for Your Vehicle
This module is a direct-fit replacement for a wide range of General Motors vehicles. While this page is dedicated to the 2006 Trailblazer EXT Transmission Control Module, it is also compatible with the following models. Please verify your specific model and options.
Partial Fitment List:
- TRAILBLAZER EXT 06 Transmission; (LH engine compartment), (8 cylinder)
- ENVOY 06-09 Transmission; (LH engine compartment)
- SAAB 9-7X 06-09 Transmission; (LH engine compartment)
- RAINIER 06-07 Transmission
- SILVERADO & SIERRA 1500/2500 07-13 Transmission; (next to battery)
- TAHOE / YUKON / SUBURBAN 07-09 Transmission; (next to battery)
- IMPALA / MONTE CARLO 06-11 Transmission; (lower air cleaner housing)
- COBALT / G5 / G6 06-10 Transmission; (LH strut tower)
- …and many more GM models from 2006-2014.
Do I need to take my vehicle to the dealer for programming?
Do I need to take my vehicle to the dealer for programming?
No. This module comes fully programmed to your vehicle’s VIN number before shipping. This eliminates the need for expensive dealership programming, making it a true plug-and-play solution.
What is a T42 TCM?
The T42 is the hardware designation for a generation of Transmission Control Modules used by General Motors primarily with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E during the mid-2000s to early 2010s.
Is there a core charge for my old part?
No, there is no core charge required for this part. You can keep your old module or dispose of it without the hassle of returning it.
Will this fix a P0700 trouble code?
A P0700 code is a general fault request from the TCM to the Engine Control Module (ECM) to turn on the Check Engine Light. While a failing TCM is a very common cause, P0700 indicates that other, more specific transmission codes are stored. This module often resolves the root cause of those specific codes, thereby clearing the P0700 as well.