Models Without PWM Solenoid

Overdrive Range - 4-3 Downshift (Converter Clutch - Released) (Models Without PWM Solenoid):

OVERDRIVE RANGE -4-3 DOWNSHIFT (CONVERTER CLUTCH - RELEASED)

"A" SHIFT SOLENOID - OFF
SECOND CLUTCH - APPLIED
1/2 SUPPORT ROLLER CLUTCH - OVERRUNNING
"B" SHIFT SOLENOID - OFF
THIRD CLUTCH - APPLIED
FORWARD BAND - APPLIED
TCC SOLENOID - OFF
THIRD ROLLER CLUTCH - HOLDING

Under light throttle acceleration, the torque converter clutch will release when the input signals sent to the PCM from the VS Sensor, TP Sensor and 4th clutch discrete switch (218) have commanded a 4-3 downshift. When the appropriate signals are received, the torque converter clutch solenoid (315) is "de-energized" or "turned off'. Line pressure and spring force at the converter clutch valve (335) moves the valve allowing Torque Converter Clutch (TCC) signal fluid to exhaust through the converter clutch solenoid (315). Converter feed fluid enters the release passage, seats No. 1 checkball (372) against apply fluid and feeds to the release side of the torque converter clutch plate. Apply fluid from the torque converter (1) is directed through the apply passage to the converter clutch valve (335) where it enters the cooler passage. TCC accumulator fluid, from the TCC accumulator piston (416), is directed: (1) through the converter clutch valve (335) and enters the release passage, and (2) to the converter clutch regulator valve (330) to control the release feel of the converter clutch plate.

A 4-3 shift occurs when the PCM "de-energizes" or "turns off current" to "A" shift solenoid (315) allowing "A" shift solenoid fluid at the 3-4 shift valve (362) to exhaust through the solenoid. Spring force at the 3-4 shift valve (362) moves the valve allowing 4th clutch apply fluid (at the 4th clutch) to be directed through the 3-4 accumulator assembly (421-428), seat No. 10 checkball (372) against 4th clutch (apply) fluid and exhaust at the 3-4 shift valve (362).

Torque Converter Clutch Solenoid (315): De-energizes, allowing the converter clutch valve (335) to move and TCC signal fluid to exhaust through the solenoid.

Converter Clutch Valve (335): When the torque converter clutch solenoid (315) is "off", converter feed fluid passes through the valve into the converter release passage and converter apply fluid is directed into the cooler passage. TCC accumulator fluid also exhausts into the release passage and acts as a bias on the converter clutch regulator valve (330).

Converter Clutch Regulator Valve (330): Uses filtered line fluid to supply regulated apply fluid to the converter clutch valve (335). Regulation is controlled by TCC accumulator and modulator fluid pressures.

TCC Accumulator Assembly (413-416): Spring force and release fluid pressure returns the TCC accumulator piston (416) to TCC "off" position.

No. 1 Checkball (372): Located in the channel plate (400), converter release fluid seats the checkball against apply fluid to allow release of the torque converter clutch plate.

"A" Shift Solenoid (315): De-energizes, allowing "A" shift solenoid fluid at the 3-4 shift valve (362) to exhaust through the solenoid.

3-4 Shift Valve (362): When "A" shift solenoid fluid exhausts, spring force moves the valve allowing 4th clutch fluid to exhaust through the valve.

3-4 Accumulator Assembly (421-428): Allows 4th clutch exhaust fluid to pass through the accumulator assembly to No. 10 checkball (372).

No. 10 Checkball (372): Located in the valve body (300), forces 4th clutch fluid through an exhaust orifice to the 3-4 shift valve (362) where it exhausts.

4th Clutch Discrete Switch (218): "Opens" a circuit to the PCM to signal that the transaxle is no longer operating in Overdrive Range - Fourth Gear.

NOTE: Under light accelerating conditions, normally the torque converter clutch will release prior to the transaxle making a 4-3 downshift. However, depending on throttle angle, vehicle load and road conditions, torque converter clutch release and a 4-3 shift may occur at the same time.