If you’re dealing with the headaches of a faulty transmission in your 2006-2007 Buick Rainier, you’ve come to the right place. As a technician with over two decades of experience under the hood, I’ve seen countless GM vehicles, including the Rainier, get sidelined by a failing Transmission Control Module (TCM). Symptoms like sudden, harsh shifts, getting stuck in one gear, or a persistent check engine light can make your reliable SUV feel unpredictable. This isn’t just an annoyance—it’s a critical failure that impacts drivability and safety.
This T42 series TCM, part number 24234503, is the definitive solution. It’s not just a replacement part; it’s a complete, ready-to-install fix. We pre-program it to your Buick’s specific Vehicle Identification Number (VIN) before it ships. This crucial step ensures the module communicates flawlessly with your vehicle’s engine computer and other systems, eliminating the need for an expensive and time-consuming trip to the dealership for programming. It’s designed to restore the precise, smooth shifting you expect from your vehicle’s 4L60E or 4L65E automatic transmission.
A Technician’s Notebook
I remember a 2007 Rainier that came into the shop with a classic case of intermittent TCM failure. The owner said it would drive perfectly for days, then suddenly slam into gear at a stoplight or refuse to upshift on the highway. We couldn’t replicate the issue in the bay, and the only code stored was a generic P0700 (Transmission Control System Malfunction). After checking the wiring and fluid, experience pointed directly to the T42 module. These units, often mounted in the engine bay, are susceptible to heat and vibration, which can cause internal solder joints to fail over time. Replacing it with a pre-programmed module solved the issue instantly, saving the customer from chasing an electrical ghost for weeks.
Is Your Rainier Exhibiting These Telltale Signs?
A failing 2006-2007 Rainier TCM can manifest in several ways. If you’re noticing any of the following, it’s a strong indicator that your module needs replacement:
- ✔ Erratic or jarringly hard shifts between gears.
- ✔ The transmission feels like it’s slipping or hesitating to engage.
- ✔ Your vehicle is stuck in “limp mode,” often locked in 2nd or 3rd gear.
- ✔ The Check Engine Light or a dedicated transmission warning light is illuminated.
- ✔ Diagnostic Trouble Codes (DTCs) like P0700, P0750-P0758 (solenoid circuit faults), or other transmission-related codes are present.
- ✔ A noticeable drop in fuel economy due to inefficient shifting.
Your Step-by-Step Installation Guide
One of the best parts about this solution is its simplicity. For most DIYers with basic tools, this is a job you can complete in your own driveway in under 30 minutes.
- Safety First: Before you begin, disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and help reset the vehicle’s computer systems.
- Locate the Module: On the Buick Rainier, the TCM is typically found in the engine compartment. Check near the air cleaner box or on the driver’s side (LH) of the engine bay. It’s a silver box with electrical connectors.
- Swap the Part: Carefully unplug the wire harness connectors. Then, unbolt the old module from its mounting bracket. Secure the new, pre-programmed module in its place and firmly reconnect the wiring harnesses.
- Final Steps: Reconnect the battery terminal. Start the vehicle and let it idle for a few minutes. While the module is plug-and-play, it’s always good practice to use a basic OBD2 scan tool to clear any old fault codes from the computer’s memory.
Confirmed Vehicle Compatibility
This module is a direct-fit replacement for the 2006-2007 Rainier TCM and is also compatible with a wide range of other GM vehicles that use the T42 controller. Please verify your part number or contact us for fitment confirmation.
- ✔ Buick: Rainier (2006-2007), LaCrosse, Lucerne, Allure, Rendezvous
- ✔ Chevrolet: Silverado, Tahoe, Suburban, Express, Impala, Cobalt, HHR, Monte Carlo, Colorado, Avalanche
- ✔ GMC: Sierra, Yukon, Savana, Envoy, Canyon
- ✔ Pontiac: G6, Grand Prix, G5, Pursuit, Montana
- ✔ Cadillac: DTS
- ✔ Saturn: Vue, Aura, Ion
- ✔ Hummer: H3
- ✔ Saab: 9-7X
This module replaces part numbers: 24234503, 24242391, 24252114, 24230461, 24234274, 24235340, and more.
Frequently Asked Questions
Does this module really not require dealer programming?
That’s correct. We handle all the programming here by flashing the module with your vehicle’s VIN and the latest GM software updates. It will arrive ready for plug-and-play installation.
What tools do I need for installation?
You’ll only need basic hand tools, typically a small socket set or wrench to remove the module’s mounting bolts and a tool to loosen the battery terminal. No specialized equipment is required.
Is there a core charge for my old part?
No, there is no core charge. You can keep your old module or dispose of it without the hassle of sending it back.
What is the warranty on this 2006-2007 Rainier TCM?
This part is backed by our comprehensive one-year warranty, giving you peace of mind and confidence in your repair.
Will this fix a P0700 code?
A P0700 code is a generic fault code indicating the TCM has detected a problem. While this module often resolves the root cause (like a faulty solenoid circuit driver), you should ensure other components like wiring and solenoids are in good condition. In most cases where the module itself is the failure point, this part is the correct fix.