If you rely on your 2006-2014 GMC Savana 3500 for work, you know that transmission trouble means costly downtime. When your van starts shifting erratically, hesitating, or gets stuck in limp mode, the problem often isn’t the transmission itself, but its electronic brain: the Transmission Control Module (TCM). I’ve seen it countless times in my shop—a perfectly good transmission condemned when all it needed was a reliable, correctly programmed TCM. This T42 Transmission Control Module, part number 24239926, is the definitive solution to get your workhorse back on the road without the high cost and hassle of a dealership visit.
This isn’t just a part; it’s a complete fix. We pre-program each module to your vehicle’s specific VIN, loading the latest GM software updates. This ensures it communicates perfectly with your van’s engine computer and other systems right out of the box. You can clear those persistent trouble codes like P0700 (Transmission Control System Malfunction) or various solenoid codes for good, restoring the crisp, predictable shifting you depend on.
Is Your Van Showing These Telltale Signs?
A failing TCM can manifest in several ways that are often misdiagnosed. If you’re experiencing any of the following, this module is likely the solution you need:
- ✔ Harsh, slamming shifts or unpredictable gear changes.
- ✔ The vehicle feels like it’s stuck in one gear (often 2nd or 3rd), a condition known as “limp mode.”
- ✔ Your Check Engine Light or Transmission Warning Light is on.
- ✔ Diagnostic trouble codes (DTCs) such as P0700, P0750, P0753, P0758 are present.
- ✔ A noticeable drop in fuel economy or a delay when shifting from Park to Drive or Reverse.
- ✔ Complete loss of communication with the module, preventing the vehicle from starting or shifting.
From the Diagnostic Bay: The Ghost in the Transmission
A contractor brought his ’09 Savana 3500 into my shop, frustrated. Another garage told him he needed a full transmission rebuild—a $4,000+ job. The van was shifting hard from 1st to 2nd and occasionally wouldn’t shift at all. I hooked up my pro-level scan tool and saw a P0758 code (Shift Solenoid B Electrical). While this can indicate a bad solenoid, my experience with these T42 modules screamed otherwise. The voltage readings to the solenoid were erratic. Instead of tearing down the transmission, we swapped in a VIN-programmed Savana 3500 Transmission Module. The total repair time was under an hour. The van shifted perfectly, the code was gone, and the customer saved thousands. It’s a classic case of the ‘brain’ failing, not the ‘body’.
A Straightforward Guide to Your TCM Replacement
Replacing the TCM on these vans is a job most DIYers or any professional mechanic can handle quickly. The location is typically easy to access, getting you back to work fast.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the onboard systems.
- Locate the Module: On the Savana and Express vans, the TCM is typically found in the engine compartment on the right-hand (passenger) side. Check near the battery or on the firewall.
- Disconnect and Remove: Carefully unplug the electrical connectors. They have locking tabs, so don’t force them. Once disconnected, unbolt the old module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed TCM into place. Reconnect the electrical connectors, ensuring they click securely into place.
- Final Steps: Reconnect the battery terminal. While the module is plug-and-play, it’s best practice to use a basic scan tool to clear any stored DTCs from the vehicle’s memory. Start the engine and test drive to confirm smooth shifting.
Verified Vehicle Compatibility List
This T42 TCM is a direct replacement for part number 24239926 and is interchangeable with a wide range of other GM part numbers, including 24252114, 24234503, and 24242391. It fits the following vehicles:
- GMC SAVANA 3500 VAN (2006-2014) – Transmission; (RH engine compartment)
- Chevrolet EXPRESS 3500 VAN (2006-2014) – Transmission; (RH engine compartment)
- GMC SAVANA 2500 VAN (2006-2014) – Transmission; (RH engine compartment)
- Chevrolet EXPRESS 2500 VAN (2006-2014) – Transmission; (RH engine compartment)
- GMC SAVANA 1500 VAN (2006-2014) – Transmission; (RH engine compartment)
- Chevrolet EXPRESS 1500 VAN (2006-2014) – Transmission; (RH engine compartment)
- Chevrolet Silverado & GMC Sierra (2007-2013) – See full fitment list for specific options.
- Chevrolet Tahoe & GMC Yukon (2007-2009) – See full fitment list for specific options.
- …and many other GM cars, trucks, and SUVs from 2006-2014.
Frequently Asked Questions
What exactly is VIN programming?
VIN programming means we load your vehicle’s unique 17-digit Vehicle Identification Number into the module before shipping. This ensures the TCM has the correct software and calibration files for your specific engine, transmission, and options, making it a true plug-and-play part.
Do I need to take my van to a dealer after installation?
No. Because this module is pre-programmed to your VIN, no further programming or trips to the dealership are required. This saves you significant time and money.
Is this a difficult part to install myself?
For most individuals with basic mechanical skills, this is a very straightforward installation. It typically involves disconnecting the battery, unplugging a few connectors, and removing a few bolts. On a Savana van, it’s easily accessible in the engine bay and usually takes less than 30 minutes.
Will this fix a “No Communication” issue with my old TCM?
Yes, in most cases. A complete loss of communication is a common failure mode for these modules. If your scan tool cannot connect to the TCM, replacing it with this programmed unit will typically restore communication and allow the vehicle to function correctly.
Is there a core charge for my old part?
No, we do not require a core charge. You can keep your old module or dispose of it without the hassle of shipping it back.