W T E C I I I E L E C T R O N I C C O N T R O L S T R O U B L E S H O O T I N G M A N U A L
GENERAL DESCRIPTION
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Figure 1–4. Pushbutton Shift Selectors
1–4.
SPEED SENSORS (Figure 1–5)
Three speed sensors — engine speed, turbine speed, and output speed — provide information to the ECU. The
engine speed signal is generated by ribs on the shell of the torque converter pump. The turbine speed signal is
generated by the rotating-clutch housing spline contours. The output speed signal is generated by a toothed
member attached to the output shaft (except for the MD 3070, where the toothed member is the transfer case idler
gear). The speed ratios between the various speed sensors allow the ECU to determine if the transmission is in the
selected range. Speed sensor information is also used to control the timing of clutch apply pressures, resulting in
the smoothest shifts possible. Hydraulic problems are detected by comparing the speed sensor information for the
current range to that range’s speed sensor information stored in the ECU memory.
Figure 1–5. Speed Sensors
