Restore Smooth Shifting to Your 2006-2011 Chevrolet HHR
If you’re dealing with the frustration of a Chevrolet HHR that bangs into gear, refuses to shift, or is stuck in limp mode, you’re not alone. As a technician with over two decades of experience, I’ve seen countless cases where the Transmission Control Module (TCM) is the culprit. The T42 TCM, like this part number 24239926, is the brain of your automatic transmission. It processes data from various sensors to command precise gear changes and torque converter operation. When it fails, the symptoms can range from annoying to debilitating, often triggering a check engine light and leaving you stranded.
Don’t let a faulty module sideline your reliable HHR. This OEM-quality replacement T42 TCM is the definitive solution to get your vehicle driving like new again. The most significant benefit is that it arrives at your door pre-programmed to your vehicle’s specific VIN. This completely eliminates the need for an expensive trip to the dealership for programming. It’s a true plug-and-play fix designed for both professional mechanics and savvy DIYers who want to save time and money. By installing this module, you’re not just replacing a part; you’re restoring the precise electronic control your transmission needs for optimal performance, fuel economy, and longevity.
A Technician’s Notebook: The P0700 Code Mystery
A customer brought in a 2009 HHR with a check engine light and harsh 1-2 shifts. The scanner showed a generic P0700 code, which simply means the TCM has requested the light. Digging deeper, we found a solenoid performance code. The shop down the street had already replaced the solenoid inside the transmission, but the problem persisted. This is a classic scenario I’ve seen dozens of times. The issue wasn’t the solenoid itself, but the TCM’s internal driver circuit for that solenoid. We installed a VIN-programmed T42 TCM, cleared the codes, and the car shifted perfectly. The customer saved hundreds by avoiding an unnecessary transmission teardown.
Is Your HHR Showing These Transmission Faults?
A failing TCM can manifest in several ways. If you’re experiencing any of the following, it’s a strong indicator that your 2006-2011 HHR Transmission Control Module needs replacement.
- ✔ Harsh, erratic, or delayed gear shifts.
- ✔ Vehicle is stuck in a single gear (limp mode), often 2nd or 3rd.
- ✔ Check Engine Light or Transmission Warning Light is illuminated.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700, P0750, or other solenoid-related faults.
- ✔ Complete loss of upshifting or downshifting capabilities.
- ✔ Noticeable decrease in fuel efficiency.
- ✔ Intermittent communication loss with the module.
A Straightforward Guide to Your HHR TCM Installation
Replacing the 2006-2011 HHR Transmission Control Module is a job most DIYers can complete in under 30 minutes with basic hand tools. On the HHR, it’s conveniently located in the engine compartment.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the vehicle’s electronic systems.
- Locate the Module: On the Chevrolet HHR, the TCM is typically found in the left-hand (driver’s side) of the engine compartment.
- Disconnect and Remove: Carefully unplug the electrical connectors from the old TCM. Then, unbolt the module from its mounting bracket and remove it from the vehicle.
- Install the New Module: Bolt the new, VIN-programmed TCM into place. Securely reconnect the electrical harnesses, ensuring they click into place.
- Final Steps: Reconnect the negative battery terminal. While the module is pre-programmed, it’s best practice to use a scan tool to clear any stored DTCs from the vehicle’s memory. Start the vehicle and take it for a test drive to confirm smooth shifting.
Verified Vehicle Compatibility
This T42 Transmission Control Module is a direct-fit replacement for a wide range of General Motors vehicles. While this listing focuses on the 2006-2011 HHR Transmission Control Module, it is also compatible with the following models. Always verify the part number 24239926 or one of its interchanges matches your original unit.
- Chevrolet: HHR (2006-2011), Cobalt, Impala, Malibu, Monte Carlo, Tahoe, Silverado, Express, Avalanche, Colorado
- GMC: Yukon, Sierra, Savana, Canyon, Envoy
- Pontiac: G5, G6, Grand Prix, Pursuit
- Saturn: Aura, Ion, Vue
- Buick: LaCrosse, Lucerne, Allure, Rainier, Rendezvous
- Cadillac: DTS
- Hummer: H3
- Saab: 9-7X
This part interchanges with numerous service numbers, including: 24252114, 24234503, 24230461, 24234274, 24239224, and more.
Frequently Asked Questions
Do I need to program this module at a dealership?
No. This module comes fully programmed to your vehicle’s VIN number. It is ready for installation right out of the box, saving you time and money.
Is there a core charge for my old part?
No, there is no core charge. You can keep your old part without any hassle or need to return it.
What tools are required for installation on an HHR?
Installation typically requires only basic hand tools, such as a socket set to remove the mounting bolts and a tool to disconnect the battery terminal. No specialized equipment is needed.
Will this fix a P0700 trouble code?
Yes, in many cases. A P0700 code indicates a fault has been registered within the TCM. If the TCM itself is the source of the fault (due to internal failure), replacing it with this programmed unit will resolve the issue and allow the code to be cleared.
How does VIN programming work?
During checkout, you will provide your vehicle’s 17-digit VIN. We use this number to load the exact GM-specified software and calibrations for your specific vehicle configuration onto the module before shipping it to you.