Automatic Transmission - Overhaul - 4R100: Description
The 4R100 transmission is a fully automatic, electronically controlled, 4-speed automatic overdrive transmission. Transmission consists of torque converter clutch, 6 multiple-disc friction clutches, one band, 2 sprag one-way clutches, a roller one-way clutch and 3 planetary gearsets. See Fig 1.
Shift control solenoids provide gear selection and are controlled by Electronic Engine Control (EEC) microprocessor. For additional information on EEC-V system, refer to appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
EEC system has self-diagnostic capabilities. Fault codes for faulty engine and transmission sensors, switches and circuits are stored in Powertrain Control Module (PCM) and may be retrieved to aid diagnosis and repair.
On vehicles equipped with Power Take-Off (PTO), transmission changes hydraulic passages for 3-4 shift valve. This allows coast clutch to be applied in "P", "R" or "N" positions, during PTO. Non-PTO transmissions have a source of fluid under line pressure to 3-4 shift valve from manual valve (OD circuit). PTO transmission has a line circuit as source of fluid. Non-PTO transmissions have an exhaust path for coast clutch through reverse circuit. PTO transmissions have a separate exhaust path for coast clutch. See Fig 2 and Fig 3 .
PTO operates in "P" or "N" positions with vehicle stationary, or in "R", "D", "2" or "1" positions with vehicle moving. When PTO operation occurs in "D", 4th gear is inhibited and coast braking occurs in 1st, 2nd and 3rd gears. During PTO operation, PCM turns on Coast Clutch Solenoid (CCS), and allows engine power to be transmitted through input shaft to PTO drive gear on coast clutch cylinder.
There are 2 types of Torque Converter Clutch (TCC) solenoids used. An On/Off solenoid is used on gasoline engines, and a modulated solenoid is used on diesel engines.