Restore Smooth Shifting to Your Chevy HHR
If you’re experiencing erratic shifting, a check engine light, or your 2006-2011 Chevy HHR is stuck in limp mode, a failing Transmission Control Module (TCM) is often the culprit. As a technician with over two decades of experience, I’ve seen countless drivers worry about a costly transmission rebuild when the real issue was electronic. This T42 series TCM, part number 24234274, is the brain of your automatic transmission, responsible for executing precise gear changes and ensuring optimal performance. Replacing it can be the most effective and economical solution to get your HHR driving like new again.
This isn’t just a part; it’s a complete solution. We pre-program each module to your vehicle’s specific VIN, eliminating the need for expensive dealership visits for programming. This ensures that once installed, the module communicates flawlessly with your vehicle’s engine computer and other systems, restoring the smooth, predictable operation you depend on. This is the definitive fix for many common transmission-related diagnostic trouble codes (DTCs) and performance issues in your 2006-2011 HHR Transmission Control Module.
From the Diagnostic Bay: The Case of the Hesitant HHR
A customer brought in a 2009 HHR with a classic complaint: intermittent harsh shifting and the car would sometimes refuse to shift out of 2nd gear. They had already been quoted over $2,000 for transmission work at another shop. After plugging in my scan tool, I saw a P0700 (Transmission Control System Malfunction) and a solenoid circuit code. Instead of jumping to conclusions, I checked the TCM’s live data. The commands were being sent, but the results were erratic. Experience told me this pointed to an internal failure in the module itself, likely from heat cycles and age. We installed one of our VIN-programmed T42 modules, and in less than an hour of shop time, the HHR was shifting perfectly. The customer saved a significant amount of money by correctly diagnosing the electronic failure first.
Is Your HHR Showing These Transmission Red Flags?
A faulty TCM can manifest in several ways. If you notice any of the following, it’s a strong indicator that your 2006-2011 HHR Transmission Control Module may need replacement. Ignoring these signs can lead to further transmission damage.
- ✔ Harsh, banging shifts or delayed gear engagement.
- ✔ Vehicle is stuck in a single gear (limp mode), often 2nd or 3rd.
- ✔ The check engine light or transmission warning light is illuminated.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700, P0750, P0753, or other solenoid-related faults.
- ✔ Unexplained drops in fuel economy.
- ✔ The transmission seems to slip between gears or fails to downshift when slowing down.
DIY-Friendly Installation for Your HHR
This module is designed for a straightforward installation that a confident DIYer can complete in their own garage. For the Chevy HHR, the TCM is conveniently located in the engine compartment. Follow these steps for a successful replacement.
- Safety First: Before you begin, disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the vehicle’s computer systems.
- Locate the Module: On the HHR, the TCM is typically found in the left-hand (driver’s side) of the engine compartment, often near the strut tower. It’s a silver box with electrical connectors.
- Disconnect and Remove: Carefully unplug the wiring harness connectors. They have locking tabs that need to be released. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed TCM into place. Securely plug in the wiring harness connectors, making sure they click to confirm they are fully seated.
- Final Steps: Reconnect the negative battery terminal. While the module is plug-and-play, it’s always a good practice to use a basic OBD2 scan tool to clear any stored fault codes from the previous module’s failure. Start the vehicle and take it for a test drive to confirm smooth operation.
Verified Fitment for Your General Motors Vehicle
While this is the specified part for the 2006-2011 HHR, this versatile T42 TCM also serves as a direct replacement for a wide range of GM cars, trucks, and SUVs. It is interchangeable with part numbers 24252114, 24234503, 24230461, and more. Please confirm your vehicle is on the list below.
This part will fit these makes and models with these options:
- HHR 06-11 Transmission; (LH engine compartment)
- COBALT 06-10 Transmission; (LH strut tower)
- G5 07-10 Transmission; (LH strut tower)
- G6 06-10 Transmission; (LH strut tower)
- IMPALA 06-11 Transmission; (lower air cleaner housing)
- MALIBU 06-10 Transmission; (LH frame rail)
- MONTE CARLO 06-07 Transmission; (lower air cleaner housing)
- TAHOE 07-09 Transmission; (next to battery)
- SILVERADO 1500 PICKUP 07-13 Transmission; (next to battery)
- EXPRESS/SAVANA VANS 06-14 Transmission; (RH engine compartment)
- And many more models including select years of the Envoy, Yukon, Sierra, LaCrosse, Lucerne, DTS, Grand Prix, Saturn Vue, and Hummer H3. Please check the full fitment list for details.
Frequently Asked Questions
Why is VIN programming so important for this part?
VIN programming loads your vehicle’s specific software and calibrations onto the TCM. This ensures it communicates correctly with the engine and transmission, controlling shift points, torque converter lockup, and line pressure precisely as the manufacturer intended. Without it, the vehicle may not start, shift properly, or may set new error codes.
Is this a difficult part for a DIY mechanic to install?
No, this is one of the more accessible electronic repairs. For the 2006-2011 HHR, the TCM is located in the engine bay and requires only basic hand tools to access and replace. The entire process typically takes less than 30 minutes.
Do I need to send my old TCM back (core charge)?
No, there is no core charge for this part. You can keep or dispose of your old module without any hassle or extra fees.
What if I install this and still have shifting problems?
While this module fixes the most common electronic causes of shifting issues, transmission problems can also be mechanical (like worn clutches or bad solenoids). If problems persist, it’s a sign that further diagnosis of the transmission’s internal components is needed. However, starting with a known-good, correctly programmed TCM is a critical first step in the diagnostic process.
Will this part fix a P0700 trouble code?
A P0700 code is a general fault request from the TCM to the main engine computer to turn on the check engine light. A failing TCM is a very common reason for this code to appear, often alongside more specific transmission codes. Replacing a faulty 2006-2011 HHR Transmission Control Module is a primary fix for a P0700 code when the module itself is the source of the failure.