Restore Your HHR’s Shifting Performance
If you’re dealing with the frustrating and unpredictable behavior of a failing transmission control module in your 2006-2011 Chevrolet HHR, you’ve come to the right place. As a technician with over two decades of experience, I’ve seen firsthand how a faulty TCM can make a reliable vehicle feel unsafe and unpredictable. This isn’t just an inconvenience; it’s a critical failure that can leave you stranded. This T42 Transmission Control Module, part number 24239926, is the definitive solution to restore the crisp, smooth shifting your HHR had from the factory.
The core of the problem often lies in the module’s inability to correctly interpret sensor data and command the transmission’s solenoids. This results in the harsh bangs, delayed shifts, and warning lights that are all too common. Our module solves this by arriving at your door fully programmed to your vehicle’s specific VIN. This means no expensive trips to the dealership for programming—it’s a true plug-and-play fix that you can perform right in your driveway.
Is Your HHR Exhibiting These Transmission Faults?
A failing TCM will give you clear warning signs. If you’re experiencing any of the following, it’s highly likely this module is the culprit. In my shop, these symptoms are the classic indicators we look for when diagnosing a 2006-2011 HHR TCM issue.
- ✔ Abrupt, harsh, or erratic gear shifts.
- ✔ The vehicle gets 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 (Transmission Control System Malfunction), P0750-P0758 (Shift Solenoid codes), or other communication errors.
- ✔ Failure to upshift or downshift properly, leading to poor acceleration and bad fuel economy.
- ✔ A noticeable delay when shifting from Park into Drive or Reverse.
Case Study: The HHR That Wouldn’t Shift
A customer brought in a 2009 HHR with an intermittent but severe shifting problem. They’d already replaced a couple of shift solenoids at another shop, but the issue persisted. The car would drive fine for a day, then suddenly start banging into gear and throw a P0700 code. After confirming the wiring harness was intact, we focused on the TCM. The internal circuitry was failing under heat, causing erratic commands. We installed one of our VIN-programmed T42 modules, and the problem was solved instantly. It’s a textbook example of why correctly diagnosing the module first can save hundreds in unnecessary parts and labor.
DIY-Friendly Installation Guide for Your HHR
Replacing the 2006-2011 HHR TCM is a straightforward job that most DIY enthusiasts can complete in under an hour with basic hand tools. This module is specifically designed for a hassle-free installation.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work.
- Locate the Module: On the Chevrolet HHR, the TCM is conveniently located in the left-hand (driver’s side) engine compartment. It’s typically mounted near the strut tower.
- Disconnect and Remove: Carefully unplug the electrical connectors. Note the locking tabs to avoid damage. Once disconnected, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new VIN-programmed TCM into place and securely reconnect the electrical connectors.
- Final Steps: Reconnect the negative battery terminal. While the module is pre-programmed, it’s good practice to use a basic scan tool to clear any stored fault codes from the vehicle’s memory. Start the vehicle and test drive to confirm smooth operation.
Verified Vehicle Compatibility
This T42 TCM is engineered for a precise fit and function in a wide range of General Motors vehicles. While it is the correct part for the 2006-2011 HHR, it also fits many other models. Please verify your part number (24239926 or an interchange number) for a guaranteed match.
- Chevrolet HHR (2006-2011) – LH engine compartment
- Chevrolet Cobalt (2006-2010) – LH strut tower
- Chevrolet Impala / Monte Carlo (2006-2011) – Lower air cleaner housing
- Chevrolet Silverado / Tahoe / Suburban (2007-2013) – Next to battery
- GMC Sierra / Yukon (2007-2013) – Next to battery
- Pontiac G6 (2006-2010) – LH strut tower
- Saturn Aura / Vue (2007-2010) – LH frame rail or front engine compartment
- …and many more GM models from 2006-2014.
Frequently Asked Questions
Do I need to program this 2006-2011 HHR TCM?
No. We handle all the programming for you. Simply provide your vehicle’s VIN at checkout, and the module will arrive ready for immediate installation, saving you a trip to the dealership.
What tools are required for installation?
You’ll only need basic hand tools, typically a socket set to remove the mounting bolts and possibly a small flathead screwdriver to help release the connector clips. No special diagnostic equipment is required.
Is this a reliable, long-term fix?
Absolutely. This module is built to meet or exceed OEM specifications and addresses common failure points of the original units. It comes with a one-year warranty for your peace of mind.
Will this clear my P0700 check engine light code?
Yes. If the code is being caused by a faulty TCM, which is the most common reason for a P0700 code, this replacement part will resolve the underlying issue. After installation, you should clear the codes with a scan tool for the light to go off immediately.