Overhaul - A4AF2: Operation

Shift lever has 6 positions. Shift lever controls manual valve. Shift lever also controls input signal of range switch which is mounted on transaxle. Transaxle range switch delivers an input signal to TCM to indicate shift lever position. The TCM uses input signal and operates shift control solenoid valves to control transaxle shifting.

The TCM controls transaxle shift points and hydraulic pressure to various friction elements. The TCM calculates shift points from input devices and transmits electrical signal to appropriate Shift Control Solenoid Valves (SCSV) and Pressure Control Solenoid Valve (PCSV), mounted on valve body assembly to control transaxle shifting. The TCM controls damper clutch (torque converter lock-up) by operating Damper Clutch Control Solenoid Valve (DCCSV), located on valve body assembly.

An overdrive switch is mounted on driver's side of shift lever. When overdrive switch is depressed to the ON position, transaxle will automatically upshift to overdrive and O/D OFF indicator light on instrument panel will be off.

When overdrive switch is released to the OFF position, transaxle will not upshift to overdrive and O/D OFF indicator light on instrument panel will come on.

A range switch is located on passenger's side of shift lever, near console. Range switch contains an ECON (economy) mode and NORM (normal) mode. When range switch is depressed to the NORM (normal) mode, an input signal is delivered to TCM, and TCM changes shift points to provide maximum performance. When range switch is released to the ECON (economy) mode, an input signal is delivered to TCM, and TCM changes shift points to provide maximum fuel economy.

NOTE: If engine coolant temperature is less than 68°F (20°C), transaxle will remain in ECON mode even if range switch is in NORM mode. When range switch is in ECON mode and vehicle speed exceeds 60 MPH, transaxle will not downshift when accelerator pedal is depressed. Range switch must be in NORM mode for transaxle to downshift.

The TCM contains self-diagnostic system, which stores fault code if failure or problem exists in transaxle electronic control system. Fault codes may be retrieved to determine transaxle problem area. Fault code may be referred to as Diagnostic Trouble Code (DTC). For information on electronic transaxle components, see appropriate ELECTRONIC CONTROLS article.

Transaxle is equipped with shift and key interlock systems. Shift interlock system prevents shift lever from being moved from Park position unless brake pedal is depressed, ignition is on and release button on side of shift lever is depressed.

The key interlock system prevents ignition key from being turned to LOCK position unless shift lever is in Park position. For additional information on shift and key interlock systems, see appropriate ELECTRONIC CONTROLS article.