If your 2006-2007 Saturn ION is suffering from erratic shifting, getting stuck in gear, or has an illuminated check engine light, you’re likely dealing with a failing Transmission Control Module (TCM). As an automotive diagnostician with over two decades of experience, I’ve seen firsthand how a faulty TCM can cripple an otherwise healthy vehicle. This T42 Transmission Control Module, part number 24243921, is the definitive solution to restore your car’s performance and drivability.
This isn’t just a replacement part; it’s a complete, ready-to-install fix. We pre-program each module to your vehicle’s specific VIN, ensuring it communicates flawlessly with your car’s systems right out of the box. This critical step eliminates the need for expensive dealership programming, saving you time and money. The TCM is the electronic brain of your automatic transmission, responsible for executing smooth gear changes, managing torque converter lockup for fuel efficiency, and monitoring transmission health. When it fails, you get the frustrating symptoms that you’re likely experiencing now. This module is engineered to meet or exceed original equipment standards, providing a dependable, long-term solution.
Case Study: The Elusive Limp Mode on a Saturn ION
A customer brought in a 2007 Saturn ION stuck in what we call ‘limp mode’—it wouldn’t shift out of 3rd gear. They had already spent money at another shop replacing a couple of shift solenoids based on a P0753 code, but the problem persisted. After a quick scan, I saw the P0700 (Transmission Control System Malfunction) alongside the solenoid code. In my experience, especially with these GM platforms, when you have persistent, seemingly random transmission codes, the TCM itself is often the root cause. The internal circuits weaken over time from heat and vibration. We installed one of our VIN-programmed T42 modules, cleared the codes, and the car shifted perfectly on the test drive. The customer was back on the road in under an hour, problem solved for good.
Is Your Saturn ION Showing These Transmission Warning Signs?
- ✔️ Harsh, delayed, or unpredictable gear shifts.
- ✔️ Vehicle is stuck in one gear (limp mode) and won’t shift up or down.
- ✔️ Check Engine Light or Transmission Warning Light is on.
- ✔️ Diagnostic Trouble Codes (DTCs) are present, such as P0700, P0750, P0753, or other solenoid-related faults.
- ✔️ A noticeable drop in fuel economy.
- ✔️ The transmission seems to slip out of gear or fails to engage properly from Park.
DIY-Friendly Installation: Get Your Saturn Shifting Smoothly
One of the best features of this module is its straightforward installation. You can do this in your own driveway with basic hand tools in under 30 minutes.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
- Locate the Module: On the 2006-2007 Saturn ION, the TCM is located in the engine bay, tucked behind the driver’s side (LH) strut tower.
- Swap the Part: Carefully unplug the electrical connectors from the old module. Unbolt it from its mounting bracket, and then install the new module in its place.
- Reconnect and Finalize: Securely plug the connectors into your new TCM. Reconnect the battery terminal. It’s a good practice to use a basic OBD2 scanner to clear any stored fault codes after installation.
- Test Drive: Start the car and take it for a drive to confirm that the shifting issues are resolved.
Verified Vehicle Compatibility
This T42 TCM is a direct replacement for part number 24243921 and other interchangeable numbers like 24252114, 24234503, and 24243901. While it is compatible with a wide range of General Motors vehicles, this listing is specifically for the 2006-2007 ION TCM. Please see the full list below for other potential applications.
Do I need to take this part to a dealer for programming?
Do I need to take this part to a dealer for programming?
No. Every module is pre-programmed to your vehicle’s VIN before it ships. This makes it a true plug-and-play solution, saving you the time, cost, and hassle of a dealership visit.
Where is the TCM located on my 2006 Saturn ION?
You will find the Transmission Control Module in the engine compartment, located behind the driver’s side (LH) strut tower.
Will this fix a P0700 trouble code?
In many cases, yes. A P0700 code is a general fault code that simply means the TCM has detected a problem and has requested the check engine light. Replacing a faulty TCM often resolves the underlying issue that triggers the P0700 code.
Is there a core charge for my old part?
No, there is no core charge. You can keep your old part or dispose of it without needing to send it back, simplifying your repair process.