Hello all , I hope this is the correct forum to post my question under. When I lose overdrive and torque converter lockup on my 1993 4L80-E transmission, I spray engine degreaser then blast with carburator cleaner around the outside of the fuel injection pump (driver side) .

This last time the trick didn't work, so I took off the throttle position sensor from the passenger side of the pump and took it apart to clean it. This helped smooth the shifts and there were no more delayed upshifts, but still no over-drive or lock up. I even disconnected the batteries to clear the computer.

This same effect happened long ago when I discovered one of the thin wires broke off the computer harness connector (I remove the computer at the end of each day to prevent its theft.) After I fixed the wire the trans shifted normal.

Is there an electronic solenoid that needs replacing on the trans? Thank you in advance for any suggestions.

Frank