Is Your Chevy HHR Shifting Erratically or Stuck in Limp Mode?
If your 2006-2011 Chevrolet HHR is giving you transmission headaches—like harsh, banging shifts, getting stuck in 2nd or 3rd gear, or throwing a check engine light with codes like P0700—you’re not alone. Over my 20+ years in automotive diagnostics, I’ve seen countless GM vehicles with these exact issues. The culprit is almost always a failing Transmission Control Module (TCM). This isn’t just an annoyance; it affects your vehicle’s performance, safety, and fuel economy. This VIN-programmed T42 TCM is the definitive, dealership-free solution to get your HHR running smoothly again.
Expert Pro Tip: Check Your Connectors First
Before you replace the TCM on your HHR, take a moment to inspect the main electrical connector that plugs into the module. These are located in the engine bay (left-hand side) and are exposed to the elements. I’ve seen cases where corrosion or a bent pin on the harness side was causing intermittent communication errors that mimicked a bad module. A quick spray with electronics cleaner and ensuring a snug fit can sometimes solve the problem, but more often than not, it’s a sign the internal circuitry of the original TCM is failing.
Diagnosing a Faulty HHR Transmission Control Module
A failing TCM can manifest in several ways, often starting as an intermittent problem before becoming a constant issue. If you’re experiencing any of the following, it’s a strong indicator that your module needs replacement:
- ✔ Harsh Shifting & Delayed Engagement: Your HHR might slam into gear or hesitate when shifting from Park to Drive or Reverse.
- ✔ Stuck in Gear (Limp Mode): The transmission may refuse to shift past 2nd or 3rd gear as a protective measure, severely limiting your speed.
- ✔ Warning Lights: The Check Engine Light or a specific transmission warning light will illuminate on your dash.
- ✔ Diagnostic Trouble Codes (DTCs): A scan tool will often show a P0700 (Transmission Control System Malfunction) code, which is a general fault, frequently accompanied by specific solenoid codes (e.g., P0751, P0756) or communication errors.
- ✔ No Upshifting or Downshifting: The vehicle may struggle to accelerate or fail to downshift when you slow down, causing a jerky ride.
Plug-and-Play Installation: No Dealer Visit Required
One of the biggest advantages of this module is that it arrives pre-programmed to your HHR’s specific Vehicle Identification Number (VIN). This means you can skip the expensive trip to the dealership for programming. The installation is straightforward for a DIYer with basic tools.
- 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 2006-2011 HHR, the TCM is located in the engine compartment on the driver’s side (LH side). It’s a silver box with electrical connectors.
- Disconnect and Remove: Carefully unclip the electrical harnesses from the old module. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed HHR Transmission Control Module into place and securely reconnect the electrical harnesses. You should hear a ‘click’ as they lock in.
- Reconnect and Finalize: Reconnect the negative battery terminal. While the system may reset, it’s best practice to use a standard OBD2 scan tool to clear any stored fault codes from the vehicle’s memory. Start the vehicle and test drive to confirm smooth shifting.
Guaranteed Compatibility and Reliability
This T42 TCM is built to meet or exceed original equipment standards, ensuring long-lasting performance. It is a direct replacement for part number 24230461 and is interchangeable with a wide range of other GM service numbers, including 24252114, 24234503, 24242391, and more. We stand behind our electronics with a one-year warranty, giving you peace of mind with your purchase.