Fix Your Sierra’s Shifting Problems for Good

If you’re dealing with a GMC Sierra that’s shifting harshly, getting stuck in gear, or throwing transmission codes, you know how frustrating it can be. As a technician with over two decades of experience, I’ve seen countless trucks come into the shop with these exact issues. More often than not, the culprit isn’t a catastrophic transmission failure, but a faulty Transmission Control Module (TCM). This VIN-programmed T42 TCM, part number 24235340, is the direct-fit, reliable solution designed to restore your truck’s performance and get you back on the road with confidence.

The TCM is the brain of your automatic transmission, controlling everything from shift points to torque converter lockup. When it fails, communication breaks down, leading to the erratic behavior you’re experiencing. Our module solves this by arriving pre-programmed to your truck’s specific VIN. This means no expensive trips to the dealership for programming—it’s a true plug-and-play fix that you can often do yourself in your own driveway.

Diagnosing a Faulty 2007-2013 Sierra 1500 TCM

A failing TCM in a 2007-2013 Sierra 1500 can mimic other, more serious transmission problems. Before you assume the worst, check for these tell-tale signs. A faulty module can cause inconsistent communication between the engine and transmission, resulting in poor performance, decreased fuel economy, and dashboard warning lights. Replacing it is often the most effective and economical first step in diagnostics.

Is Your Truck’s Transmission Acting Up?

• ✔ Harsh, erratic, or delayed gear shifts.
• ✔ Vehicle is stuck in “limp mode” (usually second or third gear).
• ✔ Check Engine Light or Transmission Warning Light is illuminated.
• ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700, P0750, or other solenoid-related faults.
• ✔ Failure to upshift or downshift properly.
• ✔ A noticeable decrease in fuel efficiency.
• ✔ Intermittent loss of communication with the module.

A Straightforward Guide to Installation

1. ✔ Safety First: Disconnect the negative terminal from your truck’s battery to prevent any electrical shorts and to help reset the vehicle’s electronic systems.
2. ✔ Locate the TCM: On most 2007-2013 Sierra 1500 models, the TCM is conveniently located in the engine bay, right next to the battery. It’s a silver box with electrical connectors.
3. ✔ Disconnect and Remove: Carefully unplug the electrical harnesses from the old module. Press the release tabs firmly. Then, unbolt the module from its mounting bracket.
4. ✔ Install the New Module: Bolt the new, VIN-programmed TCM into place. Securely plug in the electrical connectors, making sure they click to confirm a solid connection.
5. ✔ Reconnect and Verify: Reconnect the negative battery terminal. Start the truck and allow it to idle for a few minutes. Use a basic OBD-II scan tool to clear any stored fault codes. Take a test drive to confirm that shifting is smooth and all warning lights are off.

Verified Fitment for Your GM Truck or SUV

This T42 TCM is a direct replacement for part number 24235340 and other service numbers. While this page focuses on the 2007-2013 Sierra 1500 TCM, it is also compatible with a wide range of GM vehicles equipped with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E. Please verify your part number or consult the list below.

• GMC Sierra 1500 Pickup (2007-2013): Located next to battery. (2007 models are new body style with smooth door skin).
• Chevrolet Silverado 1500 Pickup (2007-2013): Located next to battery. (2007 models are new body style with smooth door skin).
• GMC/Chevrolet Vans (Savana, Express 1500/2500/3500, 2006-2014): Located in RH engine compartment.
• GMC/Chevrolet SUVs (Yukon, Tahoe, Suburban, Avalanche, 2007-2009): Located next to battery.
• Other GM Models: Fits various Buick, Cadillac, Pontiac, Saturn, Hummer, and Saab models from 2006-2014. Please check the detailed fitment list from the source data if your vehicle is not a Sierra.