What are the problems with the Buick 4L80E transmission?

The 4L80E transmission is known for sensor problems. The input and output speed sensors often fail or misfire, causing a variety of shifting problems—including erratic shifting, shifting slips, hard or soft shifting—or may cease shifting entirely.

What was the neutral switch on the 4T60-E transmission?

Earlier versions of the 4T65-E transmission had an external gear position switch (which was part of the neutral safety switch that bolted onto the transmission under where the gear shift cable arm hooks up, just like the 4T60-E had). This switch tells the PCM what position the shifter is in.

What causes a Buick transmission to stop shifting?

The input and output speed sensors often fail or misfire, causing a variety of shifting problems—including erratic shifting, shifting slips, hard or soft shifting—or may cease shifting entirely. These sensors should always be checked first in the event of transmission problems with these models. How to Adjust the Transmission …

Where is the electrical connector on a 4T65 transmission?

All 4T65-E’s came with a cast aluminum side cover, and the electrical connector for these transmissions is located in the top of the side cover which faces the driver’s side of the vehicle (see picture). Aside from that, the 4T65-E looks very similar to the 4T60-E and is also very similar, mechanically, to the 4T60-E.

What causes bad gears in a Buick T400?

Since modulators control shift firmness, a bad modulator can result in slipping gears. Buick’s T400 transmissions contain a plastic accumulator piston which often breaks. These pistons can be replaced by aluminum models in rebuilt transmissions.

Why does my torque converter shudder when I Turn on the engine?

As mentioned, converter shudder is usually temperature related. As transmission fluid recycles back through the engine turbine, it picks up frictional heat.