[ASJT3]

Originally Posted by Blue Bowtie

For further information:

1993 4L60Es were used in trucks only. Not available in F-Bodies, B-Bodies, or Y-Bodies.

1994 is fully interchangeable with 1993 4L60E with no modifications. Those years are a Non-PWM transmission, meaning that the converter lock up apply strategy is an digital arrangement. The trans has an 11-pin main electrical connector. There is a one-piece TCC control valve in the valve bodym and the early design 3-2 valve.

1995 is a stand-alone year for the 4L60E. It will not interchange with any other year. This is a PWM lockup transmission with an extra solenoid added to the valve body to control the pulsed lock up scheme of the torque converter clutch. The unit used a 12-pin main case electrical connector and required an extra wire in the transmission harness and different PCM to control the PWM circuit. The units have "PWM" cast in the front pump body. The front pump internal passages different to match new TCC strategy, along with a two-piece TCC control valve in valve body. It retained the early design 3-2 valve. A 1993-1994 PCM will not function with the pulsed TCC scheme and will tend to burn up the convertedr clutch and 3-4 clutches. The 1996 PCM is also not compatible with early 3-2 control solenoid.

1996/1997: The 3-2 downshift control was changed to a digital scheme. The TCC solenoid was changed to a 20-31Ω unit, from the previous 10-15Ω solenoid. The 3-2 control valve was changed to the second design valve. The easiest way to identify the valve is in that the second design valve will fall out as soon as the solenoid is removed. The first design has a separate port plug and circlip. The TCC solenoid remained 10-15Ω, which is the same as 1995. Most 1995-and up units will have "PWM" cast in the pump housing. The 1996/97 pump itself is the same as 1995, but it will not exchange with a 1995 unless the 3-2 solenoid is also changed. Also the 1994/95 PCM will not operate the 20-31Ω 3-2 solenoid and will generate a powertrain DTV, then force the transmission into "limp" mode.

Thanks for this info. Are the 98/99 transmissions same as 96/97?