Transmission Overview
The 4T60E is a modified version of GM’s 440 transaxle, with full electronic control. It uses two shift solenoids and a converter clutch solenoid; some have a pulse width modulated solenoid to control the converter clutch apply feel. These solenoids receive power all the time through terminal E; the computer supplies ground to energize the individual solenoids.

Unlike most other electronic transaxles, the 4T60E still has a modulator to provide an engine load signal, which the transmission uses to control line pressure. In general, the standard "dual red-stripe" modulator should work fine on most units; however, there is a special modulator valve available for vehicles being operated at high altitudes.

Terminal Identification
Here’s a breakdown of the individual connector terminals:

Checking the Shift Pattern
Here’s how to connect your signal box to the transaxle connector, to check the signals from the computer to the transaxle: 

This is the shift pattern you should see with your signal monitor:

Forcing the Shift
Here’s the manual shift pattern you can expect with the transaxle in failsafe:

Here’s how to force the 4T40E transaxle to shift electrically:

First Gear
In first gear, the computer supplies ground to both shift solenoids.

Second Gear
To shift into second gear, the computer releases ground from solenoid A; only solenoid B is grounded.

Third Gear
To shift into third gear, the computer releases ground from solenoid B; neither solenoid is grounded.

Fourth Gear
To shift into fourth gear, the computer grounds solenoid A; the gray lines are the connections necessary to apply the converter clutch.

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