Transmission Description
The E4OD transmission is a fully automatic, electronically controlled, four-speed unit with a torque converter clutch. The main operating components of the E4OD transmission include a torque converter clutch, six multiple-disc friction clutches, one band, one sprag one-way clutch and two roller one-way clutches that provide for the desired function of three planetary gear sets.
Transmission gear selection in the (D) range and converter clutch operation is controlled by the powertrain control module (PCM) (12A650). Operating conditions are relayed to powertrain control module by various sensors throughout the vehicle. The powertrain control module compares these conditions with electronically stored parameters and logically determines how the transmission should operate.
A torque converter (7902) couples the engine to the transmission gearset via the input shaft (7017) and the torque converter impeller hub. The impeller hub provides engine rpm to the positive displacement pump. The flow from the pump is proportional to engine rpm, and excess pump capacity is exhausted back to the pump inlet.
The input shaft transfers power into the transmission gearset. The power input is controlled by the application of the torque converter clutch, which is scheduled through the powertrain control module.
The application of the piston plate effectively replaces the hydraulic coupling between the converter cover and the turbine with a mechanical coupling between the converter cover and the turbine hub. This mechanical coupling helps improve fuel economy and wide-open throttle performance by eliminating converter slip.
Transmission shift selection and torque converter clutch operation are controlled by the PCM. They are calibrated to provide the optimal transmission state. This state is commanded to the transmission solenoid body.
In the (D) range, automatic operation of all four gears is possible. The transmission control switch, located on the vehicle's shift lever disables overdrive operation and enables automatic operation through the first three gears. Whenever the ignition switch is turned on, the vehicle will automatically provide overdrive operation regardless of the switch position the last time the vehicle was running.
Manual gear selection is available in the 1 and 2 range. Second gear is commanded when the gearshift selector lever is in the 2 range and when downshifted into the 1 range at speeds above approximately 56 km/h (35 mph) (for diesel 48 km/h [30 mph]). First gear is commanded in the 1 range at start-ups and when downshifted into 1 range below approximately 56 km/h (35 mph) (for diesel 48 km/h [30 mph]). Any reference to intermediate brake drum or direct clutch cylinder are one and the same.
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Programmable Speedometer/Odometer Module (PSOM):
Description: The programmable speedometer/odometer module receives input from the rear brake anti-lock sensor, which is mounted on the rear axle differential housing. The PSOM processes this input signal information and relays it to the powertrain control module and the speed control module. This signal tells the powertrain control module the vehicle speed in miles per hour (mph). Used as an input in determining shift scheduling and electronic pressure control.
Symptoms: Harsh engagements, firm shift feel, abnormal shift schedule, unexpected downshifts may occur at closed throttle, abnormal torque converter clutch operation or engages only at wide-open throttle (WOT). May flash transmission control indicator lamp.
Diagnostic Trouble Codes: 452, P0500, P1500, P1501, P0503
