Restore Smooth, Reliable Shifting to Your Chevy 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’ve likely pinpointed the culprit: a failing Transmission Control Module (TCM). As a technician with over two decades of experience under the hood, I’ve seen countless GM vehicles, especially those with the dependable 4-speed automatic, suffer from these exact electronic issues. This isn’t just an annoyance; it’s a critical failure that affects your vehicle’s performance, fuel economy, and safety. This T42 series TCM, part number 24243901, is the definitive solution, arriving pre-programmed to your HHR’s specific VIN for a true plug-and-play repair.
What Does a Transmission Control Module Do?
Think of the TCM as the dedicated brain for your automatic transmission. It constantly analyzes data from engine speed, vehicle speed, and throttle position sensors to command precise, perfectly timed gear shifts. It also controls the torque converter clutch lock-up for better efficiency on the highway. When this brain starts to falter due to heat, vibration, or internal electronic failure, the transmission loses its guide, leading to the chaotic and unpredictable behavior you’re experiencing. Replacing it with our expertly programmed 2006-2011 HHR TCM restores that crucial communication, making your transmission operate as it did from the factory.
From the Diagnostic Bay: The HHR That Wouldn’t Cooperate
I remember a 2009 HHR that came into my shop with a maddeningly intermittent problem. The owner complained of harsh 1-2 shifts and occasionally getting stuck in 3rd gear, but only after driving for 20+ minutes. The initial scan showed a generic P0700 transmission fault code. Many techs might jump to replacing shift solenoids, an internal and costly job. However, based on my experience with these platforms, I suspected the TCM was failing once it got hot. We swapped in a pre-programmed T42 module, and the problem vanished instantly. The customer saved hundreds on unnecessary labor and parts because we addressed the root cause—the failing electronic controller—first.
Common Signs of a Failing GM T42 TCM
- âś” Harsh, delayed, or erratic gear shifts that make driving uncomfortable.
- âś” The vehicle enters “limp mode,” often getting stuck in 2nd or 3rd gear.
- âś” Check Engine Light or Transmission warning light is illuminated on the dash.
- âś” Diagnostic Trouble Codes (DTCs) are present, such as P0700, P0750, P0753, P0758, or other solenoid-related faults.
- âś” A complete loss of shifting ability or failure to engage a gear from Park.
- âś” Noticeably worse fuel mileage due to inefficient shifting and torque converter operation.
A Straightforward Guide to Installation
- âś” Safety First: Begin by disconnecting the negative terminal from your vehicle’s battery to prevent any electrical shorts and help reset the vehicle’s adaptive memory.
- âś” Locate the Module: On the 2006-2011 Chevrolet HHR, the TCM is conveniently located in the engine compartment, typically on the driver’s side near the strut tower.
- âś” Disconnect and Remove: Carefully unplug the electrical connectors from the old TCM. Press the release tabs firmly to avoid damaging the clips. Then, unbolt the module from its mounting bracket.
- âś” Install the New TCM: Mount the new, VIN-programmed module in place and securely fasten the bolts. Reconnect the electrical harnesses, ensuring they click into place.
- âś” Final Steps: Reconnect the negative battery terminal. While our VIN programming handles the critical setup, it’s always best practice to use a scan tool to clear any stored fault codes from the vehicle’s memory. Start the car and enjoy your smooth-shifting transmission!
Verified Fitment For Your Vehicle
This module is a direct replacement for part number 24243901 and other interchangeable service numbers. While it is guaranteed to fit the 2006-2011 HHR TCM application, it is also compatible with a wide range of other GM vehicles. Please see the comprehensive list below to confirm fitment for other models.
Partial Fitment List:
- Chevrolet HHR (2006-2011) – Transmission; (LH engine compartment)
- Chevrolet Cobalt (2006-2010) – Transmission; (LH strut tower)
- Pontiac G5 / G6 (2006-2010) – Transmission; (LH strut tower)
- Saturn Ion (2006-2007) – Transmission; (behind LH strut tower)
- Chevrolet Impala (2006-2011) – Transmission; (lower air cleaner housing)
- And many more GM cars, trucks, and SUVs from 2006-2014.
Frequently Asked Questions
Does this TCM require programming at a dealership?
No, it does not. We handle all the programming for you. Simply provide your vehicle’s VIN during checkout, and the module will arrive ready for immediate installation, saving you time and money.
Is this a difficult part to install myself?
For most DIYers with basic tools, this is a very manageable job. The TCM on the HHR is easily accessible in the engine bay, and the entire process typically takes less than 30 minutes. No special tools are required.
What is the difference between a TCM and a PCM/ECM?
The TCM (Transmission Control Module) is solely responsible for transmission functions. The PCM (Powertrain Control Module) or ECM (Engine Control Module) manages the engine. In many modern vehicles, these are separate units to handle the complex tasks of each system.
Do I need to send my old part back (core charge)?
No, there is absolutely no core charge for this part. You can keep your old module or dispose of it without any hassle or extra cost.
Will this part fix a P0700 trouble code?
A P0700 code is a general fault code indicating the TCM has detected a problem. While a faulty TCM is a very common cause, this code can also be triggered by other issues. However, if you’re experiencing shifting problems along with the code, replacing the TCM is the most probable fix.