Models With PWM Solenoid

Overdrive Range - 4-3 Downshift (Converter Clutch - Released) (Models With PWM Solenoid):

OVERDRIVE RANGE - 4-3 DOWNSHIFT (CONVERTER CLUTCH - RELEASED) (MODELS CONTAINING PWM)

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

Under light throttle acceleration, the [1][2]torque converter clutch is released when the PCM receives input signals from the VS Sensor and TP Sensor to regulate the "duty cycle" of the Pulse Width Modulated (PWM) solenoid in order to achieve a smooth disengagement of the converter clutch. Once this is achieved, the converter clutch solenoid (315) and the PWM solenoid (325) are "de-energized" or "turned off". Line pressure and spring force at the converter clutch valve (335) moves the valve to allow converter feed fluid to enter the release passage. Release pressure seats No. 1 checkball (372) against apply fluid and feeds to the release side of the torque converter clutch plate. Apply fluid in the torque converter (1) is directed through the apply passage to the converter clutch valve (335) where it enters the cooler passage. 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 passage and exhaust at the 3-4 shift valve (362).

PWM Solenoid (325): Controlled by the PCM, it modifies the PWM duty cycle to vary the feed pressure in the PWM fluid passage to the converter clutch regulator valve (330). When the PWM solenoid is "de-energized" or "turned off", full line pressure passes through the solenoid to the converter clutch regulator valve (330). This arrangement provides for accurate control of the regulated converter clutch apply and release pressure.

Converter Clutch Solenoid (315): De-energizes, allowing the converter clutch valve (335) to move and [1][2]Torque Converter Clutch (TCC) signal fluid to exhaust through the solenoid.

Converter Clutch Valve (335): When the 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.

No. 1 Checkball (372): Located in the channel plate (400), converter release fluid seats the checkball against apply fluid to allow release of the [1][2]torque converter clutch.

"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.

NOTE: Under light accelerating conditions, normally the [1][2]torque converter clutch will release pitor 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.