Restore Peak Performance to Your Allison Transmission
Is your 2001-2005 Silverado or Sierra HD truck suffering from harsh shifting, getting stuck in gear, or throwing transmission codes? Before you suspect a costly internal transmission failure, the culprit is often a faulty Transmission Control Module (TCM). As a technician with over two decades of experience, I’ve seen countless GM heavy-duty trucks sidelined by this exact issue. This replacement TCM is the definitive, hassle-free solution to get your workhorse back on the road, shifting as smoothly as it did from the factory.
This isn’t just a part; it’s a complete fix. We take all the guesswork and dealership expense out of the equation. Upon purchase, simply provide us with your vehicle’s VIN. Our experts will then program the module with the latest, most stable GM software specific to your truck. This means when it arrives at your door, it’s ready for a direct, plug-and-play installation. No need for expensive scan tools or a trip to the service center for programming—a step that can save you hundreds of dollars and significant downtime.
From the Diagnostic Bay
I remember a 2004 Silverado 2500HD that came into my shop towed in, stuck in ‘limp mode’ (3rd gear only). The owner was convinced his Allison transmission was shot and was bracing for a multi-thousand-dollar repair bill. He had a P0700 (Transmission Control System Malfunction) and a U0100 (Lost Communication with ECM/PCM). After checking the basics—fluid level, wiring harness—I focused on the TCM. These modules, mounted on the fan shroud, endure constant vibration and heat cycles, which eventually damages internal solder joints. We swapped in a pre-programmed TCM, cleared the codes, and the truck shifted perfectly. The customer saved a fortune and drove away in under an hour. This is the most common failure I see for these symptoms.
Is Your Allison Truck Showing These Signs?
- ✔ Harsh, erratic, or delayed shifting
- ✔ Getting stuck in one gear (Limp Mode)
- ✔ Check Engine Light or other transmission-related warning lights
- ✔ Diagnostic Trouble Codes (DTCs) such as P0700, U0100, or other P07xx codes
- ✔ No communication with the TCM when using a scan tool
- ✔ Inaccurate gear display on the instrument cluster
A Straightforward Guide to Installation
- ✔ Safety First: Disconnect the negative terminal from your truck’s battery.
- ✔ Locate the TCM: On these GM HD trucks, the Transmission Control Module is typically mounted on the driver’s side of the radiator fan shroud.
- ✔ Remove the Old Module: Carefully unplug the electrical connectors. Be gentle with the locking tabs, as they can become brittle over time. Then, unbolt the module from the fan shroud.
- ✔ Install the New Module: Bolt your new, pre-programmed TCM into place. Reconnect the electrical connectors, ensuring they click securely into position.
- ✔ Final Step: Reconnect the negative battery terminal. Start the truck and allow it to idle for a few minutes. Take it for a test drive to confirm that normal shifting has been restored. No further programming is required!
Verified Fitment for Your GM HD Truck
This module is a direct replacement for vehicles equipped with the 5-speed Allison automatic transmission (RPO Code M74). It is guaranteed to fit the following models:
- 2001-2005 Chevrolet Silverado 2500 HD
- 2001-2005 Chevrolet Silverado 3500
- 2001-2005 GMC Sierra 2500 HD
- 2001-2005 GMC Sierra 3500
This part directly replaces Service Numbers (SERV NO): 15768288, 15071240, 15163072, 15163073, 15169833, 15169834, 15169835, 15183963, 15187103, 15187104, 29537441, 09385220, 09387820.
Frequently Asked Questions
Why do you need my VIN?
Your VIN (Vehicle Identification Number) allows us to program the TCM with the exact software and calibrations your specific truck requires from the factory. This ensures perfect communication between the engine and transmission for optimal performance and fuel economy, and makes the part truly plug-and-play.
Is this difficult to install for a DIYer?
Not at all. The physical replacement is very straightforward, typically involving a few bolts and electrical connectors. Since we handle all the programming, you eliminate the most complex part of the job. Basic hand tools are all that’s required.
Will I need to perform a relearn procedure?
In most cases, no special relearn procedure is needed. After installation, the module will adapt to your driving style over the first 50-100 miles. Just drive normally, and the system will fine-tune its shift points.
What if my part number is slightly different?
The listed service numbers (like 15768288, 15169833, etc.) are all superseded by or are compatible with this module, part number 15169834. As long as your vehicle is listed in our fitment guide and you have the 5-speed Allison, this is the correct part for you.