THM 4L80-E – ATSG (Automatic Transmission Service Group)
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This booklet contains general description and the procedures necessary to repair, overhaul, or service the THM 4L80-E electronic overdrive automatic transmission. The THM 4L80-E is a fully automatic rear wheel drive transmission. It provides Park, Reverse, Neutral, and four forward speeds with 4th gear being overdrive.
The shift pattern is controlled electronically with two solenoids that recieve a ground signal from the Powertrain Control Module (PCM). The PCM will vary shift points and shift feel, as it is constantly interpreting numerous electronic signals from various operational sensors located on the vehicle. The PCM also controls the Torque Converter Clutch (TCC) apply speed, apply feel, and the release electronically with a solenoid.
Line pressure and shift feel are also controlled electronically with a Pressure Control Solenoid (PCS) located on the valve body. This function is also controlled by the PCM and the numerous electronic signals from the sensors.
- POWERFLOW CHART AND SHIFT SOLENOID PATTERN
- SHIFT SPEED CHART
- LINE PRESSURE TESTS
- TROUBLE SHOOTING CHARTS
- OIL PASSAGE IDENTIFICATION
- CHECK BALL LOCATIONS
- 1991-92 WIRING SCHEMATIC
- TRANSMISSION DISASSEMBLY
- TRANSMISSION ASSEMBLY PROCESS
- THRUST BEARING LOCATIONS
- TROUBLE CODE DESCRIPTION
- TORQUE SPECIFICATIONS
- UPDATED WIRE HARNESS AND CASE CONNECTOR FOR 1993
- UPDATED ELECTRONICS FOR 1994
- UPDATED CENTER LUBE SYSTEM FOR 1997
- UPDATED MANUAL 2ND BAND FOR 1999
- UPDATED OVERRUN CLUTCH FOR 2001