Fix Your Buick’s Shifting Problems for Good
If your 2006-2007 Buick Rainier is experiencing harsh shifts, delayed gear engagement, or is stuck in limp mode, the cause is often a failing Transmission Control Module (TCM). As a seasoned technician, I’ve seen countless GM vehicles with these exact issues, and a faulty TCM is the most common culprit. This T42 Transmission Control Module, part number 24241806, is the reliable, long-term solution you need. It’s the command center for your 4L60E or 4L65E transmission, managing every shift and ensuring smooth, efficient operation. Don’t let a small electronic component sideline your entire vehicle or lead to more expensive transmission damage.
A Technician’s Notebook: The Misleading Solenoid Code
A customer brought in a 2007 Envoy—which shares the same platform as your Rainier—with a check engine light and the transmission stuck in 3rd gear. The scanner showed a P0752 code for a stuck shift solenoid. A less experienced mechanic might immediately drop the transmission pan and replace the solenoid. However, after 20 years in the bay, my first step with these T42 systems is to check the TCM. The internal drivers that power those solenoids are a known failure point. We swapped in a pre-programmed TCM, cleared the codes, and the truck shifted perfectly. The solenoid was fine; the TCM was the real problem. This module saves you from unnecessary labor and diagnostic headaches.
Is Your Rainier Exhibiting These Transmission Problems?
A failing TCM will give you clear warning signs. If you’re noticing any of the following, it’s time to consider a replacement. This isn’t just about performance; it’s about safety and preventing further damage.
- ✔ Harsh, erratic, or delayed shifting that makes driving uncomfortable.
- ✔ The vehicle is stuck in a single gear (often called “limp mode”).
- ✔ Check Engine Light or Transmission Warning Light is illuminated on your dash.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as the general P0700 code or specific solenoid codes (e.g., P0750, P0752, P0753).
- ✔ A noticeable drop in fuel economy as the transmission operates inefficiently.
- ✔ The transmission feels like it’s slipping between gears or fails to downshift properly.
A Straightforward Guide to Installation
One of the biggest benefits of this module is the simple, DIY-friendly installation. You don’t need a lift or specialized tools, and the entire process can be completed in under 30 minutes in your own driveway. This module is specifically designed for your 2006-2007 Rainier Transmission Module replacement.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work.
- Locate the Module: On the Buick Rainier and similar GM SUVs like the Trailblazer and Envoy, the TCM is typically found in the engine compartment on the driver’s side (LH).
- Disconnect and Remove: Carefully unclip the electrical connectors from the old module. 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’ll hear a click when they are properly seated.
- Final Steps: Reconnect the battery terminal. While the module is plug-and-play, it’s always good practice to use a basic OBD2 scan tool to clear any lingering fault codes from the vehicle’s memory.
Verified Compatibility for Your Vehicle
This T42 TCM is a direct replacement for a wide range of General Motors vehicles equipped with 4-speed automatic transmissions. While this page is focused on the Buick Rainier, it also fits many other popular models. Please verify your part number (24241806) or use our vehicle selector for a guaranteed fit.
This part is a confirmed fit for:
- Buick Rainier: 2006-2007
- Chevrolet Trailblazer: 2006-2009 (8 cylinder)
- GMC Envoy / Envoy XL: 2006-2009 (8 cylinder)
- Saab 9-7X: 2006-2009
- …and many other GM cars, trucks, and SUVs from 2006-2014 including the Silverado, Tahoe, Impala, and more. See the full fitment list for details.
Frequently Asked Questions
What is a Transmission Control Module (TCM)?
The TCM is a computer that acts as the “brain” for your automatic transmission. It receives data from various sensors on the engine and vehicle, and uses that information to control when the transmission shifts gears, how firmly it shifts, and when the torque converter locks up for better fuel efficiency.
Why is VIN programming so important?
Each GM vehicle has specific software calibrations for its transmission based on engine size, axle ratio, and tire size. We program this module with your vehicle’s unique Vehicle Identification Number (VIN) before shipping. This ensures it works perfectly right out of the box, with optimal shift patterns and performance, and saves you a costly trip to the dealership for programming.
Is this part difficult to install for a DIYer?
Not at all. This is one of the easier electronic components to replace. It’s typically located in an accessible spot in the engine bay and only requires basic hand tools. Most customers complete the installation in under 30 minutes.
Do I need to return my old TCM? (Is there a core charge?)
No, there is no core charge for this part. You can keep your old module or dispose of it without the hassle of returning it to us, making the repair process simpler and faster for you.
What if my Check Engine Light is still on after installation?
After installing the new TCM and reconnecting the battery, any old “stored” codes should be cleared. We recommend using a standard OBD2 scanner to perform a final clear of any fault codes to ensure the system is fully reset. If a light returns, there may be another underlying issue that was masked by the faulty TCM.