To make it work, you'd need to essentially create a stand-alone transmission control system. This involves:
* Standalone Transmission Controller: You'll need a controller specifically designed to manage a 4L60E without the factory PCM. These controllers typically receive inputs from sensors (like vehicle speed, throttle position, and engine RPM) and use those inputs to control the transmission's solenoids. Several aftermarket companies offer these controllers, but they can be expensive.
* Sensor Inputs: You'll need to source and install the necessary sensors (speed sensor, throttle position sensor, etc.) to provide the controller with the information it needs. Some of these sensors might be compatible with your existing carburetor setup, while others may require adaptation or custom fabrication.
* Wiring Harness: You'll need to wire the controller to the transmission and the various sensors. This requires a good understanding of electrical systems and potentially custom wiring.
* Calibration: After installation, the controller will likely need to be calibrated to properly control the transmission's shifting characteristics. This often involves a process of trial and error, adjusting settings until you achieve optimal performance.
Why it's generally not recommended:
* Complexity: This is a significant undertaking, requiring advanced mechanical and electrical skills. The wiring alone can be a nightmare.
* Cost: The cost of the controller, sensors, wiring, and potential professional labor can quickly exceed the value of the vehicle.
* Reliability: Even with careful installation and calibration, there's a risk of reliability issues due to the complexity of the system.
* Better Alternatives: For a 1994 GMC with a carburetor, it would be far simpler and more reliable to use a transmission designed to work with a carburetor-controlled engine, such as a TH350, TH400, or a 700R4 (though even the 700R4 has some electronic components in later years). Swapping to one of these transmissions would be a significantly less complicated and less expensive project.
In short, while technically possible, using a 4L60E with a carburetor is a challenging and expensive project best left to experienced mechanics with specialized knowledge. Using a more compatible transmission is strongly recommended.
