Overhaul - RO: Operation

Shift lever has 6 positions. When shift lever is moved, manual valve on main valve body is moved by the shift cable. Shift lever also changes position of the shift position console switch, mounted near shift lever. Shift position console switch delivers an input signal to the ATCU to indicate shift lever position. The ATCU uses input signal to operate shift control solenoid valves and control transaxle shifting.

When transaxle gear combinations are engaged by clutches, power is transmitted from mainshaft to countershaft to provide different gears. Shift lever positions operate as follows:

1. "P" (Park)
   
   Front wheels lock as parking pawl engages with parking gear on countershaft. All clutches are released. Neutral safety switch, incorporated in shift position console switch, allows starting in this position.
2. "R" (Reverse)
   
   Reverse selector is engaged with countershaft reverse gear and 4th clutch is applied. Back-up light switch, incorporated in shift position console switch, allows back-up lights to operate.
3. "N" (Neutral)
   
   All clutches are released. Neutral safety switch, incorporated in shift position console switch, allows starting in this position.
4. "D" (Drive)
   
   Transaxle starts in 1st gear and upshifts automatically to 2nd, 3rd and then 4th gear. Transaxle will downshift through 3rd, 2nd and 1st gears until vehicle stops. When in 2nd, 3rd or 4th gear in this range, ATCU sends signal to operate torque converter lock-up.
5. "S" (Sport)
   
   Transaxle starts in 1st gear and upshifts automatically to 2nd gear and then 3rd gear. When "S4" switch is depressed (ON position), transaxle will shift into 4th gear ("S4") range. When in "S4" range, ATCU sends signal to operate torque converter lock-up. Transaxle will downshift through all gears on deceleration.
6. "2" (Second)
   
   Transaxle starts off and remains in 2nd gear for engine braking and better traction.

When in "S4" range or "D4", 2nd, 3rd and 4th gears, torque converter lock-up exists and transaxle mainshaft rotates at same speed as engine crankshaft. Under certain conditions, torque converter lock-up clutch is applied during deceleration. Torque converter lock-up is controlled by the ATCU. The ATCU receives various input signals and operates lock-up control solenoid valves. Operation of lock-up control solenoid valves controls the modulator pressure.

The ATCU contains self-diagnostic system, which stores fault code if failure or problem exists in transaxle electronic control system. Fault code can be retrieved to determine transaxle problem area. For information on electronic transaxle components, see RO ELECTRONIC CONTROLS article.

Transaxle is equipped with a shift and key interlock systems. The shift interlock system prevents the shift lever from being moved from "P" position unless the brake pedal is depressed and the accelerator pedal is in idle position. In case of a malfunction, shift lever can be released by placing the ignition key in the release slot near shift lever. Key interlock system prevents ignition key from being removed from ignition switch unless shift lever is in "P" position. For more information on interlock systems, see RO ELECTRONIC CONTROLS article.