Navigator 4WD V8-5.4L SOHC VIN L (1998)
Shift Solenoid: Description and Operation
TRANSMISSION SOLENOID BODY
The powertrain control module controls the E40D transmission operation through four on/off solenoids and one variable force solenoid. These
solenoids and transmission fluid temperature sensor are housed in the transmission solenoid body assembly. All are part of the transmission solenoid
body and are not replaced individually. Additionally, in 1995, the protection diodes that were on the solenoid body were moved to the powertrain
control module.
TRANSMISSION FLUID TEMPERATURE (TFT) SENSOR
The transmission fluid temperature sensor is located on the solenoid body assembly in the transmission sump. It is a temperature-sensitive device
called a thermistor. The resistance value of the transmission fluid temperature sensor will vary with temperature change.
The powertrain control module monitors voltage across the transmission fluid temperature sensor to determine the temperature of the transmission
fluid.
The powertrain control module uses this signal to determine whether a cold start shift schedule is necessary. The cold start shift schedule lowers shift
speeds to allow for the reduced performance of cold engine operation. The powertrain control module also uses the transmission fluid temperature
sensor input to adjust electronic pressure control pressure for temperature effects and to inhibit torque converter clutch operation during the warm-up
period.
COAST CLUTCH SOLENOID (CCS)
The coast clutch solenoid provides coast clutch control by shifting the coast clutch shift valve. The solenoid is activated by pressing the transmission
control switch or by selecting the 1 or 2 range with the transmission range selector lever. In MANUAL 1 and 2, the coast clutch is controlled by the
solenoid and also hydraulically as a fail-safe to ensure engine braking. In reverse, the coast clutch is controlled hydraulically and the solenoid is not
on.
TORQUE CONVERTER CLUTCH (TCC) SOLENOID
The Torque Converter Clutch Solenoid (TCC solenoid) provides torque converter clutch control by shifting the converter clutch control valve to
apply or release the torque converter clutch.
ELECTRONIC PRESSURE CONTROL (EPC) SOLENOID
CAUTION: The electronic pressure control pressure output from the variable force solenoid is NOT adjustable. Any modification to the electronic
pressure control solenoid may void the transmission warranty.
The electronic pressure control solenoid is a variable force solenoid. The variable-force type solenoid is an electrohydraulic actuator combining a
solenoid and a regulating valve. It supplies electronic pressure control that regulates transmission line pressure and line modulator pressure. This is
done by producing resisting forces to the main regulator and the line modulator circuits. These two pressures control clutch application pressures.
SHIFT SOLENOIDS A (1) AND B (2)
Shift solenoids l and 2 provide gear selection of first through fourth gears by controlling the pressure to the three shift valves.
