Description & Operation: Introduction

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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, 1 sprag one-way clutch, 2 roller one-way clutches and 3 planetary gearsets.

Input signals from sensors are sent to Powertrain Control Module (PCM). PCM can determine when time and conditions are right for a shift or converter clutch application. PCM can also determine line pressure needed to optimize shift feel.

Power Take-Off (PTO) is offered on Super Duty F-Series with 6.8L Triton, V10 gasoline and 7.3L power stroke diesel engines. During PTO operation, PCM receives a 12-volt input signal from PTO. PCM uses this signal to disable self-diagnostics and to monitor powertrain during use of PTO. PTO provides a electronic throttle kicker on 6.8L engine, that increases engine speed to 1300 RPM. On 7.3L engine, PTO increases engine speed to 1200 RPM. During PTO operation, PCM turns on Coast Clutch Solenoid (CCS) and allows engine power to be transmitted through transmission input shaft to PTO drive gear on coast clutch cylinder. When PTO operation occurs in "D" position, 4th gear is inhibited and coast braking occurs in 1st, 2nd and 3rd gear.

On vehicles equipped with 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. PTO operates in "P" or "N" positions with vehicle stationary, or in "R", "D", "2" or "1" positions with vehicle moving.

PCM controls transmission operation through 5 electronic solenoids consisting of 4 On/Off solenoids for shifting and torque converter clutch control and one variable force solenoid for line pressure control. All components are part of transmission solenoid body and are not serviceable individually. PCM has built-in self-diagnostic capability, fail-safe code and warning code display for main input sensors and solenoid valves. Fault codes for faulty engine and transmission sensors, switches and circuits are stored in PCM and may be retrieved to aid diagnosis and repair.

Shift control solenoids provide gear selection and are controlled by Electronic Engine Control (EEC) microprocessor. For additional information on EEC-V system, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.