End Frustrating Shifting Problems in Your Buick Rainier
If your 2006-2007 Buick Rainier is suffering from harsh shifts, getting stuck in gear, or throwing transmission codes, you’re not just dealing with an annoyance—you’re facing a critical drivability issue. As a technician with over two decades of experience, I’ve seen countless GM vehicles sidelined by a faulty Transmission Control Module (TCM). The TCM is the brain of your automatic transmission, and when it fails, it can cause unpredictable behavior that compromises both performance and safety. This T42 series TCM, part number 24256960, is the definitive solution, arriving expertly programmed to your vehicle’s specific VIN for a true plug-and-play repair.
A Technician’s Notebook: The Intermittent Rainier Fault
A customer brought in their ’07 Rainier, complaining of random, violent 1-2 shifts and occasionally getting stuck in 3rd gear (limp mode), but only after driving for 20+ minutes. The check engine light was on with a general P0700 code. Initial checks of the fluid and wiring showed nothing obvious. After letting the vehicle run in the bay, we finally duplicated the issue. The culprit? The original T42 TCM was failing internally due to heat soak. These modules are notorious for developing micro-fractures on the circuit board over time, leading to these exact intermittent electrical faults. Replacing it with a pre-programmed unit like this one solved the problem instantly, saving the customer from an expensive diagnostic rabbit hole.
Is Your Rainier Exhibiting These Telltale Signs?
A failing TCM doesn’t heal itself; it only gets worse. If you’re experiencing any of the following, it’s a strong indicator that your module needs replacement:
- ✔ Unpredictable, harsh, or delayed gear shifts.
- ✔ The vehicle enters “limp mode,” refusing to shift out of a single gear.
- ✔ Check Engine Light or Transmission Warning Light is illuminated.
- ✔ Diagnostic Trouble Codes (DTCs) are present, especially P0700, P0751, P0756, or other solenoid-related faults.
- ✔ A sudden drop in fuel economy or a sensation of the transmission slipping.
- ✔ Complete loss of communication with the transmission module.
DIY-Friendly Installation in Under 30 Minutes
One of the biggest advantages of this module is that the VIN programming is done for you. This eliminates the need for expensive dealership tools or appointments. For a 2006-2007 Buick Rainier, the TCM is typically found in the engine compartment. Follow these simple steps for a successful installation:
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent electrical shorts and reset the onboard systems.
- Locate the Old Module: On the Rainier, the TCM is generally located in the engine compartment. Identify the module and its wiring harness connectors.
- Swap the Modules: Carefully disconnect the electrical connectors and unbolt the old TCM. Mount the new module in its place and securely reconnect the wiring harnesses. You should hear a click as they lock in.
- Reconnect and Verify: Reattach the negative battery terminal. Start the vehicle and allow it to idle for a few moments. Check for any warning lights.
- Clear Codes: While not always necessary, it’s best practice to use a basic OBD2 scan tool to clear any stored transmission fault codes to ensure a clean slate for the new module.
Verified Compatibility for Your GM Vehicle
This T42 Transmission Control Module is a direct-fit replacement for a wide range of General Motors vehicles. While this page is focused on the 2006-2007 Rainier Transmission Control Module, it is also compatible with the following models. Please verify your vehicle and any specific options listed.
This part fits: RAINIER 06-07 Transmission. It is also an interchangeable replacement for part numbers 24252114, 24234503, 24230461, 24234274, 24235340, 24235754, 24238856, 24239224, 24239926, 24240400, 24241806, 24243901, 24243921, 24255280, 24256960, and others across many GM platforms including Chevrolet Silverado, Tahoe, Impala; GMC Sierra, Yukon; Cadillac DTS; Pontiac G6; and more.
Frequently Asked Questions
What exactly does a Transmission Control Module do?
The TCM acts as the central computer for your automatic transmission. It receives data from various sensors (like vehicle speed and engine load) and uses it to control shift points, torque converter lockup, and line pressure, ensuring smooth and efficient operation.
Why is VIN programming so important for this part?
VIN programming loads your vehicle’s specific software and calibrations onto the module. Without it, the TCM won’t communicate correctly with the engine computer and other systems, leading to shifting problems or a no-start condition. Our service saves you a mandatory and costly trip to the dealership.
Will this part require any additional programming after installation?
No. This module is delivered fully programmed and ready for installation. It is a true plug-and-play solution, designed to work immediately once installed correctly.
Is there a core charge or do I need to return my old TCM?
There is no core charge for this part. You can keep your old module or dispose of it, saving you the time and hassle of a return shipment.
Will this fix a P0700 transmission code?
A P0700 code is a general fault code indicating the TCM has detected a problem and has requested the check engine light be turned on. Often, a failing TCM is the root cause. While this module replacement is a very common fix for a P0700, it’s always wise to scan for any other specific codes (like P0751, P0756, etc.) to confirm the diagnosis.